diff --git a/.gitignore b/.gitignore
index 51d1cd386b..189eba3f0d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 node_modules/
 packages/*/node_modules
+packages/*/lib._esm
 .package_node_modules/
 obsolete/
 .DS_Store
diff --git a/misc/admin/lib/build.js b/misc/admin/lib/build.js
index 92f29d5d50..a003d48bd8 100644
--- a/misc/admin/lib/build.js
+++ b/misc/admin/lib/build.js
@@ -17,20 +17,6 @@ function setupConfig(outDir, moduleType, targetType) {
         if (info._ethers_nobuild) {
             return;
         }
-        if (targetType === "es2015") {
-            if (info["browser.esm"]) {
-                info.browser = info["browser.esm"];
-            }
-        }
-        else if (targetType === "es5") {
-            if (info["browser.umd"]) {
-                info.browser = info["browser.umd"];
-            }
-        }
-        else {
-            throw new Error("unsupported target");
-        }
-        utils_1.saveJson(filename, info, true);
         let path = path_1.resolve("packages", dirname, "tsconfig.json");
         let content = utils_1.loadJson(path);
         content.compilerOptions.outDir = outDir;
@@ -39,7 +25,7 @@ function setupConfig(outDir, moduleType, targetType) {
 }
 function setupBuild(buildModule) {
     if (buildModule) {
-        setupConfig("./lib.esm/", "es2015", "es2015");
+        setupConfig("./lib._esm/", "es2015", "es2015");
     }
     else {
         setupConfig("./lib/", "commonjs", "es5");
diff --git a/misc/admin/lib/cmds/bundle-testcases.d.ts b/misc/admin/lib/cmds/bundle-testcases.d.ts
new file mode 100644
index 0000000000..cb0ff5c3b5
--- /dev/null
+++ b/misc/admin/lib/cmds/bundle-testcases.d.ts
@@ -0,0 +1 @@
+export {};
diff --git a/misc/admin/lib/cmds/bundle-testcases.js b/misc/admin/lib/cmds/bundle-testcases.js
new file mode 100644
index 0000000000..0f0bf9923d
--- /dev/null
+++ b/misc/admin/lib/cmds/bundle-testcases.js
@@ -0,0 +1,62 @@
+"use strict";
+var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
+    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
+    return new (P || (P = Promise))(function (resolve, reject) {
+        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
+        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
+        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
+    });
+};
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+/** bundle-testcases
+ *
+ * This sript converts all the testase data (including needed
+ * text files) into a single JSON file.
+ *
+ * All gzip files (mostly .json.gz) are decompressed and recompressed
+ * using deflate, so a much more simple deflate library can be used.
+ */
+const fs_1 = __importDefault(require("fs"));
+const path_1 = require("path");
+const zlib_1 = __importDefault(require("zlib"));
+const log_1 = require("../log");
+const path_2 = require("../path");
+const config = {
+    dirs: [
+        "./input/easyseed-bip39",
+        "./testcases",
+        "./input/wordlists"
+    ]
+};
+(function () {
+    return __awaiter(this, void 0, void 0, function* () {
+        console.log(log_1.colorify.bold(`Bundling Testcase Data...`));
+        const data = { "_": JSON.stringify({ name: "browser-fs", config: config }) };
+        config.dirs.forEach((dirname) => {
+            let fulldirname = path_2.resolve("packages/testcases", dirname);
+            fs_1.default.readdirSync(fulldirname).forEach((filename) => {
+                const key = path_1.join(dirname, filename);
+                const content = fs_1.default.readFileSync(path_1.join(fulldirname, filename));
+                if (filename.split(".").pop() === "gz") {
+                    const contentData = zlib_1.default.gunzipSync(content);
+                    data[key] = String(contentData.length) + "," + zlib_1.default.deflateRawSync(contentData).toString("base64");
+                }
+                else {
+                    data[key] = content.toString("base64");
+                }
+                console.log(`  - Added ${key} (${data[key].length} bytes)`);
+            });
+        });
+        // We write it out to all needed places
+        fs_1.default.writeFileSync(path_2.resolve("packages/testcases/lib/browser-data.json"), JSON.stringify(data));
+        fs_1.default.writeFileSync(path_2.resolve("packages/testcases/lib._esm/browser-data.json"), JSON.stringify(data));
+        fs_1.default.writeFileSync(path_2.resolve("packages/testcases/lib.esm/browser-data.json"), JSON.stringify(data));
+        // Write it to the TypeScript source last, in case it is running it will
+        // be regenerated overwriting the above files, but with identical content
+        fs_1.default.writeFileSync(path_2.resolve("packages/testcases/src.ts/browser-data.json"), JSON.stringify(data));
+    });
+})();
diff --git a/misc/admin/lib/cmds/esm-alias.d.ts b/misc/admin/lib/cmds/esm-alias.d.ts
new file mode 100644
index 0000000000..cb0ff5c3b5
--- /dev/null
+++ b/misc/admin/lib/cmds/esm-alias.d.ts
@@ -0,0 +1 @@
+export {};
diff --git a/misc/admin/lib/cmds/esm-alias.js b/misc/admin/lib/cmds/esm-alias.js
new file mode 100644
index 0000000000..0abb586c84
--- /dev/null
+++ b/misc/admin/lib/cmds/esm-alias.js
@@ -0,0 +1,131 @@
+"use strict";
+var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
+    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
+    return new (P || (P = Promise))(function (resolve, reject) {
+        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
+        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
+        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
+    });
+};
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+const fs_1 = __importDefault(require("fs"));
+const path_1 = require("path");
+const depgraph_1 = require("../depgraph");
+const path_2 = require("../path");
+const utils_1 = require("../utils");
+const log_1 = require("../log");
+function diff(a, b) {
+    return (Buffer.compare(fs_1.default.readFileSync(a), fs_1.default.readFileSync(b)) !== 0);
+}
+function alias(name) {
+    return __awaiter(this, void 0, void 0, function* () {
+        console.log(`  Aliasing: ${name}`);
+        const baseDir = path_2.resolve("packages", name);
+        const info = utils_1.loadJson(path_2.resolve(baseDir, "package.json"));
+        const replacements = info["_ethers.alias"] || {};
+        const skip = Object.keys(replacements).reduce((accum, key) => {
+            const replace = replacements[key];
+            accum[replace] = true;
+            accum[replace + ".map"] = true;
+            accum[replace.replace(/\.js$/, ".d.ts")] = true;
+            return accum;
+        }, ({}));
+        const transforms = [];
+        const recurse = function (input, output) {
+            fs_1.default.readdirSync(path_1.join(baseDir, input)).forEach((filename) => {
+                const stat = fs_1.default.statSync(path_1.join(baseDir, input, filename));
+                if (stat.isDirectory()) {
+                    recurse(path_1.join(input, filename), path_1.join(output, filename));
+                    return;
+                }
+                if (skip[filename]) {
+                    return;
+                }
+                let inputFilename = filename;
+                let transform = null;
+                if (filename.match(/\.js(on)?$/)) {
+                    // JavaScript; swap in any replacement
+                    // e.g. (filename = geturl.js) => (inputFilename = browser-geturl.js)
+                    //      + transform (//# sourceMappingURL=browser-geturl.js.map) to
+                    //                  (//# sourceMappingURL=geturl.js.map)
+                    const replace = replacements[filename];
+                    // Skip!
+                    if (replace === "") {
+                        return;
+                    }
+                    if (replace) {
+                        inputFilename = replace;
+                        transform = function (content) {
+                            content = content.replace(/(\/\/# sourceMappingURL=)(.*)$/g, (all, prefix, mapFilename) => {
+                                return prefix + filename + ".map";
+                            });
+                            return content;
+                        };
+                    }
+                }
+                else if (filename.match(/\.d\.ts$/)) {
+                    // TypeScript definietion file
+                    // e.g. (filename = geturl.d.ts) => diff(geturl.d.ts, browser-geturl.d.ts)
+                    // We do not need to swap anything out, but we need to ensure
+                    // the definition of the node and browser are identical
+                    const replace = replacements[filename.replace(/\.d\.ts$/i, ".js")];
+                    // Skip!
+                    if (replace === "") {
+                        return;
+                    }
+                    if (replace) {
+                        inputFilename = replace.replace(/\.js$/i, ".d.ts");
+                        if (diff(path_1.join(baseDir, input, filename), path_1.join(baseDir, input, inputFilename))) {
+                            console.log(`Warning: TypeScript Definition files differ: ${filename} != ${inputFilename}`);
+                        }
+                    }
+                }
+                else if (filename.match(/\.map$/)) {
+                    // Map files; swap in the replacement
+                    // e.g. (filename = geturl.js.map) => (inputFilename = browser-geturl.js.map)
+                    //      + transform the map JSON to reference "geturl.js"
+                    // We need to swap in the replacement and update its data
+                    const replace = replacements[filename.replace(/\.js.map$/i, ".js")];
+                    // Skip!
+                    if (replace === "") {
+                        return;
+                    }
+                    if (replace) {
+                        inputFilename = replace + ".map";
+                        transform = function (content) {
+                            const data = JSON.parse(content);
+                            data["file"] = filename.replace(/\.js\.map$/, ".js");
+                            return JSON.stringify(data);
+                        };
+                    }
+                }
+                transforms.push({ input: path_1.join(input, inputFilename), output: path_1.join(output, filename), transform });
+            });
+        };
+        recurse("lib._esm", "lib.esm");
+        transforms.forEach(({ input, output, transform }) => {
+            const sourceFile = path_1.join(baseDir, input);
+            let content = fs_1.default.readFileSync(sourceFile).toString();
+            if (transform) {
+                content = transform(content);
+            }
+            const targetFile = path_1.join(baseDir, output);
+            const targetDir = path_1.dirname(targetFile);
+            utils_1.mkdir(targetDir);
+            fs_1.default.writeFileSync(targetFile, content);
+        });
+    });
+}
+(function () {
+    return __awaiter(this, void 0, void 0, function* () {
+        console.log(log_1.colorify.bold(`Aliasing Node ESM to Browser ESM...`));
+        const dirnames = depgraph_1.getOrdered(true);
+        for (let i = 0; i < dirnames.length; i++) {
+            yield alias(dirnames[i]);
+        }
+    });
+})();
diff --git a/misc/admin/src.ts/build.ts b/misc/admin/src.ts/build.ts
index f8ecd0c0e6..18ca63797e 100644
--- a/misc/admin/src.ts/build.ts
+++ b/misc/admin/src.ts/build.ts
@@ -18,19 +18,6 @@ function setupConfig(outDir: string, moduleType: string, targetType: string) {
 
         if (info._ethers_nobuild) { return; }
 
-        if (targetType === "es2015") {
-            if (info["browser.esm"]) {
-                info.browser = info["browser.esm"];
-            }
-        } else if (targetType === "es5") {
-            if (info["browser.umd"]) {
-                info.browser = info["browser.umd"];
-            }
-        } else {
-            throw new Error("unsupported target");
-        }
-        saveJson(filename, info, true);
-
         let path = resolve("packages", dirname, "tsconfig.json");
         let content = loadJson(path);
         content.compilerOptions.outDir = outDir;
@@ -40,7 +27,7 @@ function setupConfig(outDir: string, moduleType: string, targetType: string) {
 
 export function setupBuild(buildModule: boolean): void {
     if (buildModule) {
-        setupConfig("./lib.esm/", "es2015", "es2015");
+        setupConfig("./lib._esm/", "es2015", "es2015");
     } else {
         setupConfig("./lib/", "commonjs", "es5");
     }
diff --git a/misc/admin/src.ts/cmds/bundle-testcases.ts b/misc/admin/src.ts/cmds/bundle-testcases.ts
new file mode 100644
index 0000000000..f48bef0962
--- /dev/null
+++ b/misc/admin/src.ts/cmds/bundle-testcases.ts
@@ -0,0 +1,56 @@
+"use strict";
+
+/** bundle-testcases
+ *
+ * This sript converts all the testase data (including needed
+ * text files) into a single JSON file.
+ *
+ * All gzip files (mostly .json.gz) are decompressed and recompressed
+ * using deflate, so a much more simple deflate library can be used.
+ */
+
+
+import fs from "fs";
+import { join } from "path";
+import zlib from "zlib";
+
+import { colorify } from "../log";
+import { resolve } from "../path";
+
+const config = {
+    dirs: [
+        "./input/easyseed-bip39",
+        "./testcases",
+        "./input/wordlists"
+    ]
+};
+
+(async function() {
+    console.log(colorify.bold(`Bundling Testcase Data...`));
+
+    const data: Record<string, string> = { "_": JSON.stringify({ name: "browser-fs", config: config }) };
+
+    config.dirs.forEach((dirname) => {
+        let fulldirname = resolve("packages/testcases", dirname);
+        fs.readdirSync(fulldirname).forEach((filename) => {
+            const key = join(dirname, filename);
+            const content = fs.readFileSync(join(fulldirname, filename));
+            if (filename.split(".").pop() === "gz") {
+                const contentData = zlib.gunzipSync(content);
+                data[key] = String(contentData.length) + "," + zlib.deflateRawSync(contentData).toString("base64");
+            } else {
+                data[key] = content.toString("base64");
+            }
+            console.log(`  - Added ${ key } (${ data[key].length } bytes)`);
+        });
+    });
+
+    // We write it out to all needed places
+    fs.writeFileSync(resolve("packages/testcases/lib/browser-data.json"), JSON.stringify(data));
+    fs.writeFileSync(resolve("packages/testcases/lib._esm/browser-data.json"), JSON.stringify(data));
+    fs.writeFileSync(resolve("packages/testcases/lib.esm/browser-data.json"), JSON.stringify(data));
+
+    // Write it to the TypeScript source last, in case it is running it will
+    // be regenerated overwriting the above files, but with identical content
+    fs.writeFileSync(resolve("packages/testcases/src.ts/browser-data.json"), JSON.stringify(data));
+})();
diff --git a/misc/admin/src.ts/cmds/esm-alias.ts b/misc/admin/src.ts/cmds/esm-alias.ts
new file mode 100644
index 0000000000..c0246ea68a
--- /dev/null
+++ b/misc/admin/src.ts/cmds/esm-alias.ts
@@ -0,0 +1,123 @@
+import fs from "fs";
+import { dirname, join } from "path";
+
+import { getOrdered } from "../depgraph";
+import { resolve } from "../path";
+import { loadJson, mkdir } from "../utils";
+import { colorify } from "../log";
+
+function diff(a: string, b: string): boolean {
+    return (Buffer.compare(fs.readFileSync(a), fs.readFileSync(b)) !== 0);
+}
+
+async function alias(name: string): Promise<void> {
+    console.log(`  Aliasing: ${ name }`);
+
+    const baseDir = resolve("packages", name);
+
+    const info = loadJson(resolve(baseDir, "package.json"));
+    const replacements: Record<string, string> = info["_ethers.alias"] || { };
+    const skip = Object.keys(replacements).reduce((accum, key) => {
+        const replace = replacements[key];
+        accum[replace] = true;
+        accum[replace + ".map"] = true;
+        accum[replace.replace(/\.js$/, ".d.ts")] = true;
+        return accum;
+    }, <Record<string, boolean>>({ }));
+
+    const transforms: Array<{ input: string, output: string, transform?: (content: string) => string }> = [ ];
+    const recurse = function(input: string, output: string) {
+        fs.readdirSync(join(baseDir, input)).forEach((filename) => {
+            const stat = fs.statSync(join(baseDir, input, filename));
+            if (stat.isDirectory()) {
+                recurse(join(input, filename), join(output, filename));
+                return;
+            }
+            if (skip[filename]) { return; }
+
+            let inputFilename = filename;
+            let transform: (content: string) => string = null;
+
+            if (filename.match(/\.js(on)?$/)) {
+                // JavaScript; swap in any replacement
+                // e.g. (filename = geturl.js) => (inputFilename = browser-geturl.js)
+                //      + transform (//# sourceMappingURL=browser-geturl.js.map) to
+                //                  (//# sourceMappingURL=geturl.js.map)
+                const replace = replacements[filename];
+
+                // Skip!
+                if (replace === "") { return; }
+
+                if (replace) {
+                    inputFilename = replace;
+                    transform = function(content: string) {
+                        content = content.replace(/(\/\/# sourceMappingURL=)(.*)$/g, (all, prefix, mapFilename) => {
+                            return prefix + filename + ".map";
+                        });
+                        return content;
+                    }
+                }
+
+            } else if (filename.match(/\.d\.ts$/)) {
+                // TypeScript definietion file
+                // e.g. (filename = geturl.d.ts) => diff(geturl.d.ts, browser-geturl.d.ts)
+                // We do not need to swap anything out, but we need to ensure
+                // the definition of the node and browser are identical
+                const replace = replacements[filename.replace(/\.d\.ts$/i, ".js")];
+
+                // Skip!
+                if (replace === "") { return; }
+
+                if (replace) {
+                    inputFilename = replace.replace(/\.js$/i, ".d.ts");
+                    if (diff(join(baseDir, input, filename), join(baseDir, input, inputFilename))) {
+                        console.log(`Warning: TypeScript Definition files differ: ${ filename } != ${ inputFilename }`);
+                    }
+                }
+
+            } else if (filename.match(/\.map$/)) {
+                // Map files; swap in the replacement
+                // e.g. (filename = geturl.js.map) => (inputFilename = browser-geturl.js.map)
+                //      + transform the map JSON to reference "geturl.js"
+                // We need to swap in the replacement and update its data
+                const replace = replacements[filename.replace(/\.js.map$/i, ".js")];
+
+                // Skip!
+                if (replace === "") { return; }
+
+                if (replace) {
+                    inputFilename = replace + ".map";
+                    transform = function(content: string) {
+                        const data = JSON.parse(content);
+                        data["file"] = filename.replace(/\.js\.map$/, ".js");
+                        return JSON.stringify(data);
+                    }
+                }
+            }
+
+            transforms.push({ input: join(input, inputFilename), output: join(output, filename), transform });
+        });
+    };
+    recurse("lib._esm", "lib.esm");
+
+    transforms.forEach(({ input, output, transform }) => {
+        const sourceFile = join(baseDir, input);
+        let content = fs.readFileSync(sourceFile).toString();
+
+        if (transform) { content = transform(content); }
+
+        const targetFile = join(baseDir, output);
+        const targetDir = dirname(targetFile);
+        mkdir(targetDir);
+
+        fs.writeFileSync(targetFile, content);
+    });
+}
+
+(async function() {
+    console.log(colorify.bold(`Aliasing Node ESM to Browser ESM...`));
+    const dirnames = getOrdered(true);
+    for (let i = 0; i < dirnames.length; i++) {
+        await alias(dirnames[i]);
+    }
+})();
diff --git a/package.json b/package.json
index 9f0fc93cf9..0e345be43a 100644
--- a/package.json
+++ b/package.json
@@ -15,42 +15,43 @@
     "build": "tsc --build ./tsconfig.project.json",
     "_build-cjs": "node ./misc/admin/lib/cmds/echo 'Building CommonJS libraries...' && node ./misc/admin/lib/cmds/set-build-option cjs && npm run build",
     "_build-esm": "node ./misc/admin/lib/cmds/echo 'Building ES modules libraries...' && node ./misc/admin/lib/cmds/set-build-option esm && npm run build",
-    "clean": "node ./misc/admin/lib/cmds/echo 'Cleaning all build files...' && rm -rf packages/*/lib packages/*/lib.esm packages/*/node_modules packages/*/dist/*.js packages/*/tsconfig.tsbuildinfo node_modules .package_node_modules package-lock.json",
-    "_test-esm-dist": "rollup -c rollup-tests.config.js --configModule",
-    "_test-umd-dist": "rollup -c rollup-tests.config.js",
+    "clean": "node ./misc/admin/lib/cmds/echo 'Cleaning all build files...' && rm -rf packages/*/lib packages/*/lib._esm packages/*/lib.esm packages/*/node_modules packages/*/dist/*.js packages/*/tsconfig.tsbuildinfo node_modules .package_node_modules package-lock.json",
+    "_test-dist": "node ./misc/admin/lib/cmds/bundle-testcases && rollup -c rollup-tests.config.js",
     "_test-browser-umd": "karma start --single-run --browsers HeadlessLittleLiar karma-umd.conf.js",
     "_test-browser-esm": "karma start --single-run --browsers HeadlessLittleLiar karma-esm.conf.js",
-    "test-browser-umd": "npm run _test-umd-dist && npm run _test-browser-umd",
-    "test-browser-esm": "npm run _test-esm-dist && npm run _test-browser-esm",
+    "test-browser-umd": "npm run _test-dist && npm run _test-browser-umd",
+    "test-browser-esm": "npm run _test-dist && npm run _test-browser-esm",
     "test-coverage": "nyc --report-dir=output --reporter=lcov --reporter=text mocha --reporter ./packages/tests/reporter-keepalive ./packages/tests/lib/test-*.js | tee output/summary.txt",
     "test-node": "mocha --no-colors --reporter ./packages/tests/reporter ./packages/tests/lib/test-*.js",
-    "test-react": "npm run _test-umd-dist && npm run build-dist-shims && pushd misc/ReactNativeTestApp && ./run-tests.sh && popd",
+    "test-react": "npm run _test-dist && npm run build-dist-shims && pushd misc/ReactNativeTestApp && ./run-tests.sh && popd",
     "test": "npm run build-all && npm run test-node",
     "build-docs": "flatworm docs.wrm docs",
     "serve-docs": "node ./misc/admin/lib/cmds/serve-docs.js",
     "upload-docs": " node ./admin/cmds/upload-docs.js",
     "spell-check": "node ./misc/admin/lib/cmds/spell-check.js",
-    "build-dist-ancillary": "node ./misc/admin/lib/cmds/set-build-option esm && rollup -c rollup-ancillary.config.js",
-    "build-dist-shims": "browserify ./packages/shims/src/index.js -o ./packages/shims/dist/index.js && uglifyjs --compress --mangle --output ./packages/shims/dist/index.min.js -- ./packages/shims/dist/index.js",
-    "build-dist-umd": "node ./misc/admin/lib/cmds/set-build-option cjs browser-lang-all && rollup -c && mv ./packages/ethers/dist/ethers.umd.min.js ./packages/ethers/dist/ethers-all.umd.min.js && node ./misc/admin/lib/cmds/set-build-option cjs && rollup -c",
-    "build-dist-esm": "node ./misc/admin/lib/cmds/set-build-option esm browser-lang-all && rollup -c --configModule && mv ./packages/ethers/dist/ethers.esm.min.js ./packages/ethers/dist/ethers-all.esm.min.js && node ./misc/admin/lib/cmds/set-build-option esm && rollup -c --configModule",
-    "_build-dist": "node ./misc/admin/lib/cmds/echo 'Building dist files...' && npm run build-dist-shims && npm run build-dist-esm && npm run build-dist-ancillary && npm run build-dist-umd",
+    "_reset-build": "node ./misc/admin/lib/cmds/set-build-option cjs",
+    "_esm-alias": "node ./misc/admin/lib/cmds/echo 'Bundling ESM elliptic (lib._esm/browser-elliptic.js)...' && rollup -c rollup-pre-alias.config.js && node misc/admin/lib/cmds/esm-alias",
+    "build-libs": "node ./misc/admin/lib/cmds/update-exports.js && node ./misc/admin/lib/cmds/bundle-testcases && npm run _build-cjs && npm run _build-esm && npm _reset-build && node packages/asm/generate.js && npm run _esm-alias && chmod 755 packages/*/lib/bin/*.js",
+    "build-dist-shims": "rollup -c rollup-shims.config.js && uglifyjs --compress --mangle --output ./packages/shims/dist/index.min.js -- ./packages/shims/dist/index.js",
+    "build-dist-libs": "rollup -c rollup-dist.config.js && uglifyjs packages/ethers/dist/ethers.umd.js --output packages/ethers/dist/ethers.umd.min.js --source-map 'content=packages/ethers/dist/ethers.umd.js.map' && uglifyjs packages/ethers/dist/ethers.esm.js --output packages/ethers/dist/ethers.esm.min.js --source-map 'content=packages/ethers/dist/ethers.esm.js.map'",
+    "_build-dist": "node ./misc/admin/lib/cmds/echo 'Building dist files...' && npm run build-dist-libs && npm run build-dist-shims",
     "build-dist": "node ./misc/admin/lib/cmds/npm-skip-node8.js || npm run _build-dist",
-    "build-libs": "node ./misc/admin/lib/cmds/update-exports.js && npm run _build-cjs && npm run _build-esm && node ./misc/admin/lib/cmds/set-build-option cjs && node packages/asm/generate.js && chmod 755 packages/*/lib/bin/*.js",
     "build-all": "npm run build-libs && npm run build-dist",
     "update-versions": "npm run clean && npm install && npm run spell-check && npm run build-all && node ./misc/admin/lib/cmds/bump-versions && npm run build-all && node ./misc/admin/lib/cmds/update-hashes && node ./misc/admin/lib/cmds/update-changelog",
     "publish-all": "node ./misc/admin/lib/cmds/publish",
     "TODO-sync-github": "node ./admin/cmds/cache-github"
   },
   "devDependencies": {
-    "@erquhart/rollup-plugin-node-builtins": "2.1.5",
+    "@rollup/plugin-commonjs": "15.1.0",
+    "@rollup/plugin-json": "4.1.0",
+    "@rollup/plugin-node-resolve": "9.0.0",
+    "@rollup/plugin-replace": "2.3.3",
     "@types/assert": "^1.4.1",
     "@types/mocha": "^5.2.0",
     "@types/node": "^12.7.4",
     "@types/semver": "^7.3.4",
     "aes-js": "3.0.0",
     "aws-sdk": "2.137.0",
-    "browserify": "16.2.3",
     "diff": "4.0.1",
     "flatworm": "0.0.2-beta.5",
     "jison": "^0.4.18",
@@ -61,23 +62,21 @@
     "mocha": "^7.1.1",
     "nyc": "15.1.0",
     "rollup": "1.20.1",
-    "rollup-plugin-commonjs": "10.0.2",
-    "rollup-plugin-json": "4.0.0",
-    "rollup-plugin-node-globals": "1.4.0",
-    "rollup-plugin-node-resolve": "5.2.0",
-    "rollup-plugin-terser": "^7.0.0",
-    "rollup-pluginutils": "2.8.1",
+    "rollup-plugin-node-polyfills": "0.2.1",
+    "rollup-plugin-sourcemaps": "0.6.3",
     "scrypt-js": "3.0.1",
     "semver": "^5.6.0",
     "typescript": "3.8.3",
-    "uglify-es": "3.3.9"
+    "uglify-es": "3.3.9",
+    "webpack": "^4.44.2",
+    "webpack-cli": "4.1.0"
   },
   "dependencies": {
     "@babel/parser": "7.8.4",
     "@babel/types": "7.8.3",
-    "@ledgerhq/hw-app-eth": "5.3.0",
-    "@ledgerhq/hw-transport": "5.3.0",
-    "@ledgerhq/hw-transport-u2f": "5.3.0",
+    "@ledgerhq/hw-app-eth": "5.27.2",
+    "@ledgerhq/hw-transport": "5.26.0",
+    "@ledgerhq/hw-transport-u2f": "5.26.0",
     "@types/mocha": "^5.2.0",
     "aes-js": "3.0.0",
     "bech32": "1.1.4",
@@ -90,6 +89,7 @@
     "scrypt-js": "3.0.1",
     "solc": "0.7.1",
     "solidity-parser-antlr": "^0.3.2",
+    "tiny-inflate": "1.0.3",
     "ws": "7.2.3"
   }
 }
diff --git a/packages/abi/.npmignore b/packages/abi/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/abi/.npmignore
+++ b/packages/abi/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/abi/package.json b/packages/abi/package.json
index 5d80882589..c90960945d 100644
--- a/packages/abi/package.json
+++ b/packages/abi/package.json
@@ -19,7 +19,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/abi",
   "publishConfig": {
     "access": "public"
diff --git a/packages/abstract-provider/.npmignore b/packages/abstract-provider/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/abstract-provider/.npmignore
+++ b/packages/abstract-provider/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/abstract-provider/package.json b/packages/abstract-provider/package.json
index 47006ae073..42655941dd 100644
--- a/packages/abstract-provider/package.json
+++ b/packages/abstract-provider/package.json
@@ -17,7 +17,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/abstract-provider",
   "publishConfig": {
     "access": "public"
@@ -29,6 +29,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x87fdc7d7ee69d8c228c0e6946be702acd027a832b5a3deaa5b60e3c9f7110e58",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/abstract-signer/.npmignore b/packages/abstract-signer/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/abstract-signer/.npmignore
+++ b/packages/abstract-signer/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/abstract-signer/package.json b/packages/abstract-signer/package.json
index a1386aa074..3012f1a666 100644
--- a/packages/abstract-signer/package.json
+++ b/packages/abstract-signer/package.json
@@ -15,7 +15,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/abstract-signer",
   "publishConfig": {
     "access": "public"
@@ -27,6 +27,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x722fb4b5e18bb70cda3c2fbd250d96bacdbe7d358c4c426a73d262fc1f751845",
   "types": "./lib/index.d.ts",
   "version": "5.0.7"
diff --git a/packages/address/.npmignore b/packages/address/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/address/.npmignore
+++ b/packages/address/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/address/package.json b/packages/address/package.json
index b0c9eb5c65..fd6bf5a22c 100644
--- a/packages/address/package.json
+++ b/packages/address/package.json
@@ -5,8 +5,7 @@
     "@ethersproject/bytes": "^5.0.4",
     "@ethersproject/keccak256": "^5.0.3",
     "@ethersproject/logger": "^5.0.5",
-    "@ethersproject/rlp": "^5.0.3",
-    "bn.js": "^4.4.0"
+    "@ethersproject/rlp": "^5.0.3"
   },
   "description": "Utilities for handling Ethereum Addresses for ethers.",
   "ethereum": "donations.ethers.eth",
@@ -16,7 +15,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/address",
   "publishConfig": {
     "access": "public"
@@ -28,6 +27,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xd6263c8653bc6784fed703b8a30075630c544e3861f43ed5b49ab56ffb5d4808",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/address/src.ts/index.ts b/packages/address/src.ts/index.ts
index bba8a810cd..661d70ecf5 100644
--- a/packages/address/src.ts/index.ts
+++ b/packages/address/src.ts/index.ts
@@ -1,10 +1,7 @@
 "use strict";
 
-// We use this for base 36 maths
-import { BN } from "bn.js";
-
 import { arrayify, BytesLike, concat, hexDataLength, hexDataSlice, isHexString, stripZeros } from "@ethersproject/bytes";
-import { BigNumber, BigNumberish } from "@ethersproject/bignumber";
+import { BigNumber, BigNumberish, _base16To36, _base36To16 } from "@ethersproject/bignumber";
 import { keccak256 } from "@ethersproject/keccak256";
 import { encode } from "@ethersproject/rlp";
 
@@ -104,7 +101,7 @@ export function getAddress(address: string): string {
             logger.throwArgumentError("bad icap checksum", "address", address);
         }
 
-        result = (new BN(address.substring(4), 36)).toString(16);
+        result = _base36To16(address.substring(4));
         while (result.length < 40) { result = "0" + result; }
         result = getChecksumAddress("0x" + result);
 
@@ -124,7 +121,7 @@ export function isAddress(address: string): boolean {
 }
 
 export function getIcapAddress(address: string): string {
-    let base36 = (new BN(getAddress(address).substring(2), 16)).toString(36).toUpperCase();
+    let base36 = _base16To36(getAddress(address).substring(2)).toUpperCase();
     while (base36.length < 30) { base36 = "0" + base36; }
     return "XE" + ibanChecksum("XE00" + base36) + base36;
 }
diff --git a/packages/asm/.npmignore b/packages/asm/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/asm/.npmignore
+++ b/packages/asm/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/asm/generate.js b/packages/asm/generate.js
index 43086d66e6..612d9df620 100644
--- a/packages/asm/generate.js
+++ b/packages/asm/generate.js
@@ -11,4 +11,12 @@ const parser = new jison.Parser(grammar);
 
 const parserSource = parser.generate({ moduleName: "parser" });
 
+const esmSuffix = `
+
+// Added By ../generate.js
+const parse = exports.parse;
+export { parse, parser }
+`;
+
 fs.writeFileSync(resolve(__dirname, "./lib/_parser.js"), parserSource);
+fs.writeFileSync(resolve(__dirname, "./lib._esm/_parser.js"), parserSource + esmSuffix);
diff --git a/packages/asm/package.json b/packages/asm/package.json
index 29282de571..d34a7e63ea 100644
--- a/packages/asm/package.json
+++ b/packages/asm/package.json
@@ -12,7 +12,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/asm",
   "publishConfig": {
     "access": "public"
diff --git a/packages/base64/.npmignore b/packages/base64/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/base64/.npmignore
+++ b/packages/base64/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/base64/package.json b/packages/base64/package.json
index 3687a3ba62..037dd51b80 100644
--- a/packages/base64/package.json
+++ b/packages/base64/package.json
@@ -1,4 +1,7 @@
 {
+  "_ethers.alias": {
+    "base64.js": "browser-base64.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
   "browser": "./lib/browser.js",
   "browser.esm": "./lib.esm/browser.js",
@@ -14,7 +17,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/base64",
   "publishConfig": {
     "access": "public"
@@ -26,6 +29,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xf9edd66aa5131bf0bca2ea188265e0e333d781e4b0ef5e92090a7cef8556cb30",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/base64/src.ts/base64.ts b/packages/base64/src.ts/base64.ts
new file mode 100644
index 0000000000..c6f84a0cc2
--- /dev/null
+++ b/packages/base64/src.ts/base64.ts
@@ -0,0 +1,12 @@
+"use strict";
+
+import { arrayify, BytesLike } from "@ethersproject/bytes";
+
+
+export function decode(textData: string): Uint8Array {
+    return arrayify(new Uint8Array(Buffer.from(textData, "base64")));
+};
+
+export function encode(data: BytesLike): string {
+    return Buffer.from(arrayify(data)).toString("base64");
+}
diff --git a/packages/base64/src.ts/browser.ts b/packages/base64/src.ts/browser-base64.ts
similarity index 100%
rename from packages/base64/src.ts/browser.ts
rename to packages/base64/src.ts/browser-base64.ts
diff --git a/packages/base64/src.ts/index.ts b/packages/base64/src.ts/index.ts
index c6f84a0cc2..5abfcec429 100644
--- a/packages/base64/src.ts/index.ts
+++ b/packages/base64/src.ts/index.ts
@@ -1,12 +1,3 @@
 "use strict";
 
-import { arrayify, BytesLike } from "@ethersproject/bytes";
-
-
-export function decode(textData: string): Uint8Array {
-    return arrayify(new Uint8Array(Buffer.from(textData, "base64")));
-};
-
-export function encode(data: BytesLike): string {
-    return Buffer.from(arrayify(data)).toString("base64");
-}
+export { decode, encode } from "./base64";
diff --git a/packages/basex/.npmignore b/packages/basex/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/basex/.npmignore
+++ b/packages/basex/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/basex/package.json b/packages/basex/package.json
index ea5bdb3bd9..88ef7a44f5 100644
--- a/packages/basex/package.json
+++ b/packages/basex/package.json
@@ -12,7 +12,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/basex",
   "publishConfig": {
     "access": "public"
@@ -24,6 +24,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x680c45cf36dc0bc442c80238ff9fbfc482b7ac0486c24559c349277f395e0fa9",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/bignumber/.npmignore b/packages/bignumber/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/bignumber/.npmignore
+++ b/packages/bignumber/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/bignumber/package.json b/packages/bignumber/package.json
index b1e6d78fbf..15df04998b 100644
--- a/packages/bignumber/package.json
+++ b/packages/bignumber/package.json
@@ -26,6 +26,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x13de0d9c0138d0d056ed658b8f8744fab45fcdf4b52dcd9456bfd7285a4288ce",
   "types": "./lib/index.d.ts",
   "version": "5.0.8"
diff --git a/packages/bignumber/src.ts/bignumber.ts b/packages/bignumber/src.ts/bignumber.ts
index 285eb1ea1c..7ea760f388 100644
--- a/packages/bignumber/src.ts/bignumber.ts
+++ b/packages/bignumber/src.ts/bignumber.ts
@@ -8,7 +8,8 @@
  *
  */
 
-import { BN } from "bn.js";
+import _BN from "bn.js";
+import BN = _BN.BN;
 
 import { Bytes, Hexable, hexlify, isBytes, isHexString } from "@ethersproject/bytes";
 
@@ -334,3 +335,13 @@ function throwFault(fault: string, operation: string, value?: any): never {
 
     return logger.throwError(fault, Logger.errors.NUMERIC_FAULT, params);
 }
+
+// value should have no prefix
+export function _base36To16(value: string): string {
+    return (new BN(value, 36)).toString(16);
+}
+
+// value should have no prefix
+export function _base16To36(value: string): string {
+    return (new BN(value, 16)).toString(36);
+}
diff --git a/packages/bignumber/src.ts/index.ts b/packages/bignumber/src.ts/index.ts
index 1c8551bc58..b089018af0 100644
--- a/packages/bignumber/src.ts/index.ts
+++ b/packages/bignumber/src.ts/index.ts
@@ -1,2 +1,5 @@
 export { BigNumber, BigNumberish } from "./bignumber";
 export { formatFixed, FixedFormat, FixedNumber, parseFixed } from "./fixednumber";
+
+// Internal methods used by address
+export { _base16To36, _base36To16 } from "./bignumber";
diff --git a/packages/bytes/.npmignore b/packages/bytes/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/bytes/.npmignore
+++ b/packages/bytes/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/bytes/package.json b/packages/bytes/package.json
index 2d829be792..7436e74507 100644
--- a/packages/bytes/package.json
+++ b/packages/bytes/package.json
@@ -11,7 +11,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/bytes",
   "publishConfig": {
     "access": "public"
@@ -25,6 +25,7 @@
     "build": "tsc -p ./tsconfig.json",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x132538d3d8927299393c28ac01243ebc0e7ea34f5af1feadf23b364745f7c130",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/cli/.npmignore b/packages/cli/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/cli/.npmignore
+++ b/packages/cli/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/constants/.npmignore b/packages/constants/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/constants/.npmignore
+++ b/packages/constants/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/constants/package.json b/packages/constants/package.json
index b7e4ba5c3a..989f177158 100644
--- a/packages/constants/package.json
+++ b/packages/constants/package.json
@@ -23,6 +23,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x638edaa4b45c46158073ede9fda2c54d6c60a2f11485e693021c484076970130",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/constants/src.ts/addresses.ts b/packages/constants/src.ts/addresses.ts
new file mode 100644
index 0000000000..89a66bb37d
--- /dev/null
+++ b/packages/constants/src.ts/addresses.ts
@@ -0,0 +1,2 @@
+export const AddressZero = "0x0000000000000000000000000000000000000000";
+
diff --git a/packages/constants/src.ts/bignumbers.ts b/packages/constants/src.ts/bignumbers.ts
new file mode 100644
index 0000000000..3e827626e6
--- /dev/null
+++ b/packages/constants/src.ts/bignumbers.ts
@@ -0,0 +1,17 @@
+import { BigNumber } from "@ethersproject/bignumber";
+
+const NegativeOne: BigNumber = (/*#__PURE__*/BigNumber.from(-1));
+const Zero: BigNumber = (/*#__PURE__*/BigNumber.from(0));
+const One: BigNumber = (/*#__PURE__*/BigNumber.from(1));
+const Two: BigNumber = (/*#__PURE__*/BigNumber.from(2));
+const WeiPerEther: BigNumber = (/*#__PURE__*/BigNumber.from("1000000000000000000"));
+const MaxUint256: BigNumber = (/*#__PURE__*/BigNumber.from("0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"));
+
+export {
+    NegativeOne,
+    Zero,
+    One,
+    Two,
+    WeiPerEther,
+    MaxUint256
+};
diff --git a/packages/constants/src.ts/hashes.ts b/packages/constants/src.ts/hashes.ts
new file mode 100644
index 0000000000..d8c1eedaf0
--- /dev/null
+++ b/packages/constants/src.ts/hashes.ts
@@ -0,0 +1,2 @@
+export const HashZero = "0x0000000000000000000000000000000000000000000000000000000000000000";
+
diff --git a/packages/constants/src.ts/index.ts b/packages/constants/src.ts/index.ts
index 56a9accc74..ba301df170 100644
--- a/packages/constants/src.ts/index.ts
+++ b/packages/constants/src.ts/index.ts
@@ -1,30 +1,14 @@
 "use strict";
 
-import { BigNumber } from "@ethersproject/bignumber";
-
-const AddressZero = "0x0000000000000000000000000000000000000000";
-const HashZero = "0x0000000000000000000000000000000000000000000000000000000000000000";
-
-// NFKC (composed)             // (decomposed)
-const EtherSymbol = "\u039e";  // "\uD835\uDF63";
-
-const NegativeOne: BigNumber = BigNumber.from(-1);
-const Zero: BigNumber = BigNumber.from(0);
-const One: BigNumber = BigNumber.from(1);
-const Two: BigNumber = BigNumber.from(2);
-const WeiPerEther: BigNumber = BigNumber.from("1000000000000000000");
-const MaxUint256: BigNumber = BigNumber.from("0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
-
+export { AddressZero } from "./addresses";
 export {
-    AddressZero,
-    HashZero,
-
-    EtherSymbol,
-
     NegativeOne,
     Zero,
     One,
     Two,
     WeiPerEther,
     MaxUint256
-};
+} from "./bignumbers";
+export { HashZero } from "./hashes";
+export { EtherSymbol } from "./strings";
+
diff --git a/packages/constants/src.ts/strings.ts b/packages/constants/src.ts/strings.ts
new file mode 100644
index 0000000000..bf87422c00
--- /dev/null
+++ b/packages/constants/src.ts/strings.ts
@@ -0,0 +1,2 @@
+// NFKC (composed)             // (decomposed)
+export const EtherSymbol = "\u039e";  // "\uD835\uDF63";
diff --git a/packages/contracts/.npmignore b/packages/contracts/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/contracts/.npmignore
+++ b/packages/contracts/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/contracts/package.json b/packages/contracts/package.json
index 4781ebfdf4..9e98298585 100644
--- a/packages/contracts/package.json
+++ b/packages/contracts/package.json
@@ -31,6 +31,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x82fb83236d1d58cf1e61bbb0b5cb6c268733ce68facdc1d247aa11527808fd20",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/ethers/.npmignore b/packages/ethers/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/ethers/.npmignore
+++ b/packages/ethers/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/ethers/package.json b/packages/ethers/package.json
index eca84582bb..a5b4bc95de 100644
--- a/packages/ethers/package.json
+++ b/packages/ethers/package.json
@@ -1,6 +1,6 @@
 {
   "author": "Richard Moore <me@ricmoo.com>",
-  "browser": "./dist/ethers.umd.js",
+  "browser-old": "./dist/ethers.umd.js",
   "dependencies": {
     "@ethersproject/abi": "5.0.7",
     "@ethersproject/abstract-provider": "5.0.5",
@@ -41,7 +41,8 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./dist/ethers.esm.js",
+  "module": "./lib.esm/index.js",
+  "module-old": "./dist/ethers.esm.js",
   "name": "ethers",
   "repository": {
     "type": "git",
@@ -50,6 +51,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xf093f00a83d38639d15610b1b52db1512c582d817c0fab52d2e1f0049e748d03",
   "types": "./lib/index.d.ts",
   "version": "5.0.19"
diff --git a/packages/experimental/.npmignore b/packages/experimental/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/experimental/.npmignore
+++ b/packages/experimental/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/experimental/package.json b/packages/experimental/package.json
index a53d473425..c929ab034f 100644
--- a/packages/experimental/package.json
+++ b/packages/experimental/package.json
@@ -13,7 +13,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/experimental",
   "publishConfig": {
     "access": "public"
@@ -25,6 +25,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xe8978b5a1dbec971509704f95cd3ec691693759e40b602977ee2ee4dcaf189b0",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/experimental/src.ts/brain-wallet.ts b/packages/experimental/src.ts/brain-wallet.ts
index 1494a3d44d..fd9fbade89 100644
--- a/packages/experimental/src.ts/brain-wallet.ts
+++ b/packages/experimental/src.ts/brain-wallet.ts
@@ -2,7 +2,7 @@
 
 import { ethers } from "ethers";
 
-import { scrypt } from "scrypt-js";
+import scrypt from "scrypt-js";
 
 import { version } from "./_version";
 
@@ -34,7 +34,7 @@ export class BrainWallet extends ethers.Wallet {
             passwordBytes = ethers.utils.arrayify(password);
         }
 
-        return scrypt(passwordBytes, usernameBytes, (1 << 18), 8, 1, 32, progressCallback).then((key: Uint8Array) => {
+        return scrypt.scrypt(passwordBytes, usernameBytes, (1 << 18), 8, 1, 32, progressCallback).then((key: Uint8Array) => {
             if (legacy) {
                 return new BrainWallet(key);
 
diff --git a/packages/hardware-wallets/.npmignore b/packages/hardware-wallets/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/hardware-wallets/.npmignore
+++ b/packages/hardware-wallets/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/hardware-wallets/package.json b/packages/hardware-wallets/package.json
index ef4028e7a9..22a6f5fb35 100644
--- a/packages/hardware-wallets/package.json
+++ b/packages/hardware-wallets/package.json
@@ -1,4 +1,7 @@
 {
+  "_ethers.alias": {
+    "ledger-transport.js": "browser-ledger-transport.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
   "browser": {
     "./lib/ledger-transport.js": "./lib/browser-ledger-transport.js",
@@ -13,9 +16,9 @@
     "ethers": "./lib/browser-ethers.js"
   },
   "dependencies": {
-    "@ledgerhq/hw-app-eth": "5.3.0",
-    "@ledgerhq/hw-transport": "5.3.0",
-    "@ledgerhq/hw-transport-u2f": "5.3.0",
+    "@ledgerhq/hw-app-eth": "5.27.2",
+    "@ledgerhq/hw-transport": "5.26.0",
+    "@ledgerhq/hw-transport-u2f": "5.26.0",
     "ethers": "^5.0.13"
   },
   "description": "Hardware Wallet support for ethers.",
@@ -27,10 +30,10 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/hardware-wallets",
   "optionalDependencies": {
-    "@ledgerhq/hw-transport-node-hid": "5.3.0"
+    "@ledgerhq/hw-transport-node-hid": "5.26.0"
   },
   "publishConfig": {
     "access": "public"
diff --git a/packages/hash/.npmignore b/packages/hash/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/hash/.npmignore
+++ b/packages/hash/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/hash/package.json b/packages/hash/package.json
index 5a2753f43e..550430e2ca 100644
--- a/packages/hash/package.json
+++ b/packages/hash/package.json
@@ -30,6 +30,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xd3ced44284f7527cca27da2835c7eaeb117480dc6d459415ece6a672679cd538",
   "types": "./lib/index.d.ts",
   "version": "5.0.6"
diff --git a/packages/hdnode/.npmignore b/packages/hdnode/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/hdnode/.npmignore
+++ b/packages/hdnode/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/hdnode/package.json b/packages/hdnode/package.json
index 1185b3cb53..eed37ce978 100644
--- a/packages/hdnode/package.json
+++ b/packages/hdnode/package.json
@@ -22,7 +22,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/hdnode",
   "publishConfig": {
     "access": "public"
@@ -34,6 +34,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xc198bf952694f69869fa084578b644c4bc0541a0aaf803da3fb026cace875659",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/json-wallets/.npmignore b/packages/json-wallets/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/json-wallets/.npmignore
+++ b/packages/json-wallets/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/json-wallets/package.json b/packages/json-wallets/package.json
index c8e6b737cb..331440ee34 100644
--- a/packages/json-wallets/package.json
+++ b/packages/json-wallets/package.json
@@ -23,7 +23,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/json-wallets",
   "publishConfig": {
     "access": "public"
@@ -35,6 +35,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xb4a979c5e6fd6dff4caf32dd6f891e9301a8c3855b5674ea32ce4c8c3267b942",
   "types": "./lib/index.d.ts",
   "version": "5.0.7"
diff --git a/packages/json-wallets/src.ts/keystore.ts b/packages/json-wallets/src.ts/keystore.ts
index 490d165ee4..41ea2989ed 100644
--- a/packages/json-wallets/src.ts/keystore.ts
+++ b/packages/json-wallets/src.ts/keystore.ts
@@ -1,7 +1,7 @@
 "use strict";
 
 import aes from "aes-js";
-import * as scrypt from "scrypt-js";
+import scrypt from "scrypt-js";
 
 import { ExternallyOwnedAccount } from "@ethersproject/abstract-signer";
 import { getAddress } from "@ethersproject/address";
diff --git a/packages/keccak256/.npmignore b/packages/keccak256/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/keccak256/.npmignore
+++ b/packages/keccak256/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/keccak256/package.json b/packages/keccak256/package.json
index 7f0e931ff0..ce670d0f0d 100644
--- a/packages/keccak256/package.json
+++ b/packages/keccak256/package.json
@@ -12,7 +12,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/keccak256",
   "publishConfig": {
     "access": "public"
@@ -24,6 +24,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xa15a28050c6b479c3488697aa5fdc3dec0a74248fbfc8978aac8312c211d2cca",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/logger/.npmignore b/packages/logger/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/logger/.npmignore
+++ b/packages/logger/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/logger/package.json b/packages/logger/package.json
index 6a33db1203..42c53dd457 100644
--- a/packages/logger/package.json
+++ b/packages/logger/package.json
@@ -8,7 +8,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/logger",
   "publishConfig": {
     "access": "public"
@@ -20,6 +20,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xf9537798be6f9a5bf14202fe9222696f1340c305b68b14831fdb8d975c53de7d",
   "types": "./lib/index.d.ts",
   "version": "5.0.6"
diff --git a/packages/logger/src.ts/index.ts b/packages/logger/src.ts/index.ts
index 7edc77263e..2cb6c70ddf 100644
--- a/packages/logger/src.ts/index.ts
+++ b/packages/logger/src.ts/index.ts
@@ -336,4 +336,8 @@ export class Logger {
         }
         _logLevel = level;
     }
+
+    static from(version: string): Logger {
+        return new Logger(version);
+    }
 }
diff --git a/packages/networks/.npmignore b/packages/networks/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/networks/.npmignore
+++ b/packages/networks/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/networks/package.json b/packages/networks/package.json
index 83bfc9123e..45fd1e6134 100644
--- a/packages/networks/package.json
+++ b/packages/networks/package.json
@@ -11,7 +11,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/networks",
   "publishConfig": {
     "access": "public"
@@ -23,6 +23,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xedc2324ccf327f94bdd5488dc6b791873ff73f49022fd98fbb26da79fb304e85",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/pbkdf2/.npmignore b/packages/pbkdf2/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/pbkdf2/.npmignore
+++ b/packages/pbkdf2/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/pbkdf2/package.json b/packages/pbkdf2/package.json
index 606c33858c..05bcfe4cdd 100644
--- a/packages/pbkdf2/package.json
+++ b/packages/pbkdf2/package.json
@@ -1,8 +1,17 @@
 {
+  "_ethers.alias": {
+    "pbkdf2.js": "browser-pbkdf2.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
-  "browser": "./lib/browser.js",
-  "browser.esm": "./lib.esm/browser.js",
-  "browser.umd": "./lib/browser.js",
+  "browser": {
+    "./lib/pbkdf2": "./lib/browser-pbkdf2.js"
+  },
+  "browser.esm": {
+    "./lib.esm/pbkdf2": "./lib.esm/browser-pbkdf2.js"
+  },
+  "browser.umd": {
+    "./lib/pbkdf2": "./lib/browser-pbkdf2.js"
+  },
   "dependencies": {
     "@ethersproject/bytes": "^5.0.4",
     "@ethersproject/sha2": "^5.0.3"
@@ -16,7 +25,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/pbkdf2",
   "publishConfig": {
     "access": "public"
@@ -28,6 +37,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xdc38ff486e5c21e43a6da0dbdb35a5fc32ae529fdee17d7ce8d207863bbfce7e",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/pbkdf2/src.ts/browser.ts b/packages/pbkdf2/src.ts/browser-pbkdf2.ts
similarity index 85%
rename from packages/pbkdf2/src.ts/browser.ts
rename to packages/pbkdf2/src.ts/browser-pbkdf2.ts
index 41a5bd39dc..9203fb8860 100644
--- a/packages/pbkdf2/src.ts/browser.ts
+++ b/packages/pbkdf2/src.ts/browser-pbkdf2.ts
@@ -3,7 +3,7 @@
 import { arrayify, BytesLike, hexlify } from "@ethersproject/bytes";
 import { computeHmac, SupportedAlgorithm } from "@ethersproject/sha2";
 
-export function pbkdf2(password: BytesLike, salt: BytesLike, iterations: number, keylen: number, hashAlgorithm: SupportedAlgorithm): string {
+export function pbkdf2(password: BytesLike, salt: BytesLike, iterations: number, keylen: number, hashAlgorithm: string): string {
     password = arrayify(password);
     salt = arrayify(salt);
     let hLen;
@@ -24,7 +24,7 @@ export function pbkdf2(password: BytesLike, salt: BytesLike, iterations: number,
         block1[salt.length + 3] = i & 0xff;
 
         //let U = createHmac(password).update(block1).digest();
-        let U = arrayify(computeHmac(hashAlgorithm, password, block1));
+        let U = arrayify(computeHmac(<SupportedAlgorithm>hashAlgorithm, password, block1));
 
         if (!hLen) {
             hLen = U.length
@@ -39,7 +39,7 @@ export function pbkdf2(password: BytesLike, salt: BytesLike, iterations: number,
 
         for (let j = 1; j < iterations; j++) {
             //U = createHmac(password).update(U).digest();
-            U = arrayify(computeHmac(hashAlgorithm, password, U));
+            U = arrayify(computeHmac(<SupportedAlgorithm>hashAlgorithm, password, U));
             for (let k = 0; k < hLen; k++) T[k] ^= U[k]
         }
 
diff --git a/packages/pbkdf2/src.ts/index.ts b/packages/pbkdf2/src.ts/index.ts
index b67190e35b..a19a781c30 100644
--- a/packages/pbkdf2/src.ts/index.ts
+++ b/packages/pbkdf2/src.ts/index.ts
@@ -1,14 +1,2 @@
-"use strict";
 
-import { pbkdf2Sync as _pbkdf2 } from "crypto";
-
-import { arrayify, BytesLike, hexlify } from "@ethersproject/bytes";
-
-
-function bufferify(value: BytesLike): Buffer {
-    return Buffer.from(arrayify(value));
-}
-
-export function pbkdf2(password: BytesLike, salt: BytesLike, iterations: number, keylen: number, hashAlgorithm: string): string {
-    return hexlify(_pbkdf2(bufferify(password), bufferify(salt), iterations, keylen, hashAlgorithm));
-}
+export { pbkdf2 } from "./pbkdf2";
diff --git a/packages/pbkdf2/src.ts/pbkdf2.ts b/packages/pbkdf2/src.ts/pbkdf2.ts
new file mode 100644
index 0000000000..b67190e35b
--- /dev/null
+++ b/packages/pbkdf2/src.ts/pbkdf2.ts
@@ -0,0 +1,14 @@
+"use strict";
+
+import { pbkdf2Sync as _pbkdf2 } from "crypto";
+
+import { arrayify, BytesLike, hexlify } from "@ethersproject/bytes";
+
+
+function bufferify(value: BytesLike): Buffer {
+    return Buffer.from(arrayify(value));
+}
+
+export function pbkdf2(password: BytesLike, salt: BytesLike, iterations: number, keylen: number, hashAlgorithm: string): string {
+    return hexlify(_pbkdf2(bufferify(password), bufferify(salt), iterations, keylen, hashAlgorithm));
+}
diff --git a/packages/properties/.npmignore b/packages/properties/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/properties/.npmignore
+++ b/packages/properties/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/properties/package.json b/packages/properties/package.json
index ff7d978c05..cfd99977d8 100644
--- a/packages/properties/package.json
+++ b/packages/properties/package.json
@@ -11,7 +11,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/properties",
   "publishConfig": {
     "access": "public"
@@ -25,6 +25,7 @@
     "build": "tsc -p ./tsconfig.json",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x1150770f21e18d2b616708ecba357485be3227a8d474ff40edf9ed2603af62b4",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/providers/.npmignore b/packages/providers/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/providers/.npmignore
+++ b/packages/providers/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/providers/package.json b/packages/providers/package.json
index 7e868bd823..39802ea488 100644
--- a/packages/providers/package.json
+++ b/packages/providers/package.json
@@ -1,4 +1,11 @@
 {
+  "_ethers.alias": {
+    "browser-net.d.ts": "",
+    "browser-net.js": "",
+    "browser-net.js.map": "",
+    "ipc-provider.js": "browser-ipc-provider.js",
+    "ws.js": "browser-ws.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
   "browser": {
     "./lib/ipc-provider": "./lib/browser-ipc-provider.js",
@@ -8,7 +15,7 @@
   "browser.esm": {
     "./lib.esm/ipc-provider": "./lib.esm/browser-ipc-provider.js",
     "net": "./lib.esm/browser-net.js",
-    "ws": "./lib/browser-ws.js"
+    "ws": "./lib.esm/browser-ws.js"
   },
   "browser.umd": {
     "./lib/ipc-provider": "./lib/browser-ipc-provider.js",
@@ -44,7 +51,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/providers",
   "publishConfig": {
     "access": "public"
@@ -56,6 +63,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x75f5062536d763196c0bb7681f1de3c93f6d747b799f525295039df8c9c46503",
   "types": "./lib/index.d.ts",
   "version": "5.0.14"
diff --git a/packages/providers/src.ts/base-provider.ts b/packages/providers/src.ts/base-provider.ts
index 502af7a40c..ed7c37206a 100644
--- a/packages/providers/src.ts/base-provider.ts
+++ b/packages/providers/src.ts/base-provider.ts
@@ -16,7 +16,7 @@ import { sha256 } from "@ethersproject/sha2";
 import { toUtf8Bytes, toUtf8String } from "@ethersproject/strings";
 import { poll } from "@ethersproject/web";
 
-import { encode, toWords } from "bech32";
+import bech32 from "bech32";
 
 import { Logger } from "@ethersproject/logger";
 import { version } from "./_version";
@@ -318,9 +318,9 @@ export class Resolver implements EnsResolver {
             }
 
             if (version >= 0 && bytes.length === 2 + length && length >= 1 && length <= 75) {
-                const words = toWords(bytes.slice(2));
+                const words = bech32.toWords(bytes.slice(2));
                 words.unshift(version);
-                return encode(coinInfo.prefix, words);
+                return bech32.encode(coinInfo.prefix, words);
             }
         }
 
diff --git a/packages/providers/src.ts/browser-ipc-provider.ts b/packages/providers/src.ts/browser-ipc-provider.ts
index 1cb691a64b..1759a560ea 100644
--- a/packages/providers/src.ts/browser-ipc-provider.ts
+++ b/packages/providers/src.ts/browser-ipc-provider.ts
@@ -1,3 +1,7 @@
 "use strict";
 
-module.exports.IpcProvider = null;
+const IpcProvider: any = null;
+
+export {
+    IpcProvider
+};
diff --git a/packages/providers/src.ts/browser-net.ts b/packages/providers/src.ts/browser-net.ts
index bd540cc7d6..a347d85a8a 100644
--- a/packages/providers/src.ts/browser-net.ts
+++ b/packages/providers/src.ts/browser-net.ts
@@ -1,3 +1,3 @@
 "use strict";
 
-module.exports = { }
+export function connect() { }
diff --git a/packages/providers/src.ts/browser-ws.ts b/packages/providers/src.ts/browser-ws.ts
index 9b8e04027f..3f6f8db8dd 100644
--- a/packages/providers/src.ts/browser-ws.ts
+++ b/packages/providers/src.ts/browser-ws.ts
@@ -16,5 +16,6 @@ try {
         });
     }
 }
-
-module.exports = WS;
+//export default WS;
+//module.exports = WS;
+export { WS as WebSocket };
diff --git a/packages/providers/src.ts/ipc-provider.ts b/packages/providers/src.ts/ipc-provider.ts
index 878549aab8..c011ee8c5b 100644
--- a/packages/providers/src.ts/ipc-provider.ts
+++ b/packages/providers/src.ts/ipc-provider.ts
@@ -1,6 +1,6 @@
 "use strict";
 
-import net from "net";
+import { connect } from "net";
 
 import { defineReadOnly } from "@ethersproject/properties";
 import { Networkish } from "@ethersproject/networks";
@@ -45,7 +45,7 @@ export class IpcProvider extends JsonRpcProvider {
         return new Promise((resolve, reject) => {
             let response = Buffer.alloc(0);
 
-            let stream = net.connect(this.path);
+            let stream = connect(this.path);
 
             stream.on("data", (data) => {
                 response = Buffer.concat([ response, data ]);
diff --git a/packages/providers/src.ts/websocket-provider.ts b/packages/providers/src.ts/websocket-provider.ts
index 167a487c8a..cfa82391c0 100644
--- a/packages/providers/src.ts/websocket-provider.ts
+++ b/packages/providers/src.ts/websocket-provider.ts
@@ -1,13 +1,12 @@
 "use strict";
 
-import WebSocket from "ws";
-
 import { BigNumber } from "@ethersproject/bignumber";
 import { Network, Networkish } from "@ethersproject/networks";
 import { defineReadOnly } from "@ethersproject/properties";
 
 import { Event } from "./base-provider";
 import { JsonRpcProvider } from "./json-rpc-provider";
+import { WebSocket } from "./ws";
 
 import { Logger } from "@ethersproject/logger";
 import { version } from "./_version";
diff --git a/packages/providers/src.ts/ws.ts b/packages/providers/src.ts/ws.ts
new file mode 100644
index 0000000000..b3b7a2ed64
--- /dev/null
+++ b/packages/providers/src.ts/ws.ts
@@ -0,0 +1,3 @@
+import WebSocket from "ws";
+
+export { WebSocket }
diff --git a/packages/random/.npmignore b/packages/random/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/random/.npmignore
+++ b/packages/random/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/random/package.json b/packages/random/package.json
index 4ee57c88c7..f6cf20d9ec 100644
--- a/packages/random/package.json
+++ b/packages/random/package.json
@@ -1,8 +1,17 @@
 {
+  "_ethers.alias": {
+    "random.js": "browser-random.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
-  "browser": "./lib/browser.js",
-  "browser.esm": "./lib.esm/browser.js",
-  "browser.umd": "./lib/browser.js",
+  "browser": {
+    "./lib/random": "./lib/browser-random.js"
+  },
+  "browser.esm": {
+    "./lib/random": "./lib.esm/browser-random.js"
+  },
+  "browser.umd": {
+    "./lib/random": "./lib/browser-random.js"
+  },
   "dependencies": {
     "@ethersproject/bytes": "^5.0.4",
     "@ethersproject/logger": "^5.0.5"
@@ -16,7 +25,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/random",
   "publishConfig": {
     "access": "public"
@@ -28,6 +37,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x075d32afd4747ad55567bb9ff2da736a10911e202c04e9c61ba879688c82442a",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/random/src.ts/browser.ts b/packages/random/src.ts/browser-random.ts
similarity index 96%
rename from packages/random/src.ts/browser.ts
rename to packages/random/src.ts/browser-random.ts
index 2499c1332d..0d74b9cbd8 100644
--- a/packages/random/src.ts/browser.ts
+++ b/packages/random/src.ts/browser-random.ts
@@ -6,8 +6,6 @@ import { Logger } from "@ethersproject/logger";
 import { version } from "./_version";
 const logger = new Logger(version);
 
-export { shuffled } from "./shuffle";
-
 let anyGlobal: any = null;
 try {
     anyGlobal = (window as any);
diff --git a/packages/random/src.ts/index.ts b/packages/random/src.ts/index.ts
index 1f3b84a1e5..fb11db4d0c 100644
--- a/packages/random/src.ts/index.ts
+++ b/packages/random/src.ts/index.ts
@@ -1,12 +1,4 @@
 "use strict";
 
-import { randomBytes as _randomBytes } from "crypto";
-
-import { arrayify } from "@ethersproject/bytes";
-
+export { randomBytes } from "./random";
 export { shuffled } from "./shuffle";
-
-export function randomBytes(length: number): Uint8Array {
-    return arrayify(_randomBytes(length));
-}
-
diff --git a/packages/random/src.ts/random.ts b/packages/random/src.ts/random.ts
new file mode 100644
index 0000000000..1f7dca08f1
--- /dev/null
+++ b/packages/random/src.ts/random.ts
@@ -0,0 +1,7 @@
+import { randomBytes as _randomBytes } from "crypto";
+
+import { arrayify } from "@ethersproject/bytes";
+
+export function randomBytes(length: number): Uint8Array {
+    return arrayify(_randomBytes(length));
+}
diff --git a/packages/rlp/.npmignore b/packages/rlp/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/rlp/.npmignore
+++ b/packages/rlp/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/rlp/package.json b/packages/rlp/package.json
index 1b422d6e53..35050224a6 100644
--- a/packages/rlp/package.json
+++ b/packages/rlp/package.json
@@ -13,7 +13,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/rlp",
   "publishConfig": {
     "access": "public"
@@ -25,6 +25,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x2a870663cf91328de26e8b3e5cb1ac3004eefa78ffbdad7b08b61c2685c3f018",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/sha2/.npmignore b/packages/sha2/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/sha2/.npmignore
+++ b/packages/sha2/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/sha2/package.json b/packages/sha2/package.json
index 3318332f26..51b808d424 100644
--- a/packages/sha2/package.json
+++ b/packages/sha2/package.json
@@ -1,8 +1,17 @@
 {
+  "_ethers.alias": {
+    "sha2.js": "browser-sha2.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
-  "browser": "./lib/browser.js",
-  "browser.esm": "./lib/browser.js",
-  "browser.umd": "./lib/browser.js",
+  "browser": {
+    "./lib/sha2": "./lib/browser-sha2.js"
+  },
+  "browser.esm": {
+    "./lib.esm/sha2": "./lib.esm/browser-sha2.js"
+  },
+  "browser.umd": {
+    "./lib/sha2": "./lib/browser-sha2.js"
+  },
   "dependencies": {
     "@ethersproject/bytes": "^5.0.4",
     "@ethersproject/logger": "^5.0.5",
@@ -16,7 +25,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/sha2",
   "publishConfig": {
     "access": "public"
@@ -28,6 +37,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x7553e7409c1b5deee5301531eeb988b1acef161fb638c31a753f42bbab42b200",
   "types": "./lib/index.d.ts",
   "version": "5.0.4"
diff --git a/packages/sha2/src.ts/browser.ts b/packages/sha2/src.ts/browser-sha2.ts
similarity index 90%
rename from packages/sha2/src.ts/browser.ts
rename to packages/sha2/src.ts/browser-sha2.ts
index fba6525056..f72ac950e3 100644
--- a/packages/sha2/src.ts/browser.ts
+++ b/packages/sha2/src.ts/browser-sha2.ts
@@ -1,15 +1,16 @@
 "use strict";
 
-import * as hash from "hash.js";
+import hash from "hash.js";
+//const _ripemd160 = _hash.ripemd160;
 
 import { arrayify, BytesLike } from "@ethersproject/bytes";
 
+import { SupportedAlgorithm } from "./types";
+
 import { Logger } from "@ethersproject/logger";
 import { version } from "./_version";
 const logger = new Logger(version);
 
-export enum SupportedAlgorithm { sha256 = "sha256", sha512 = "sha512" };
-
 export function ripemd160(data: BytesLike): string {
     return "0x" + (hash.ripemd160().update(arrayify(data)).digest("hex"));
 }
@@ -22,7 +23,6 @@ export function sha512(data: BytesLike): string {
     return "0x" + (hash.sha512().update(arrayify(data)).digest("hex"));
 }
 
-
 export function computeHmac(algorithm: SupportedAlgorithm, key: BytesLike, data: BytesLike): string {
     if (!SupportedAlgorithm[algorithm]) {
         logger.throwError("unsupported algorithm " + algorithm, Logger.errors.UNSUPPORTED_OPERATION, {
diff --git a/packages/sha2/src.ts/index.ts b/packages/sha2/src.ts/index.ts
index 21aac5d82b..ac50daa8aa 100644
--- a/packages/sha2/src.ts/index.ts
+++ b/packages/sha2/src.ts/index.ts
@@ -1,38 +1,14 @@
-"use strict";
+import { computeHmac, ripemd160, sha256, sha512 } from "./sha2";
 
-import { createHash, createHmac } from 'crypto';
+import { SupportedAlgorithm } from "./types";
 
-import { arrayify, BytesLike } from '@ethersproject/bytes';
+export {
+    computeHmac,
 
-import { Logger } from "@ethersproject/logger";
-import { version } from "./_version";
-const logger = new Logger(version);
+    ripemd160,
 
-export enum SupportedAlgorithm { sha256 = "sha256", sha512 = "sha512" };
+    sha256,
+    sha512,
 
-
-export function ripemd160(data: BytesLike): string {
-    return "0x" + createHash("ripemd160").update(Buffer.from(arrayify(data))).digest("hex")
-}
-
-export function sha256(data: BytesLike): string {
-    return "0x" + createHash("sha256").update(Buffer.from(arrayify(data))).digest("hex")
-}
-
-export function sha512(data: BytesLike): string {
-    return "0x" + createHash("sha512").update(Buffer.from(arrayify(data))).digest("hex")
+    SupportedAlgorithm
 }
-
-
-export function computeHmac(algorithm: SupportedAlgorithm, key: BytesLike, data: BytesLike): string {
-    /* istanbul ignore if */
-    if (!SupportedAlgorithm[algorithm]) {
-        logger.throwError("unsupported algorithm - " + algorithm, Logger.errors.UNSUPPORTED_OPERATION, {
-            operation: "computeHmac",
-            algorithm: algorithm
-        });
-    }
-
-    return "0x" + createHmac(algorithm, Buffer.from(arrayify(key))).update(Buffer.from(arrayify(data))).digest("hex");
-}
-
diff --git a/packages/sha2/src.ts/sha2.ts b/packages/sha2/src.ts/sha2.ts
new file mode 100644
index 0000000000..71a202a50f
--- /dev/null
+++ b/packages/sha2/src.ts/sha2.ts
@@ -0,0 +1,36 @@
+"use strict";
+
+import { createHash, createHmac } from "crypto";
+
+import { arrayify, BytesLike } from "@ethersproject/bytes";
+
+import { SupportedAlgorithm } from "./types";
+
+import { Logger } from "@ethersproject/logger";
+import { version } from "./_version";
+const logger = new Logger(version);
+
+export function ripemd160(data: BytesLike): string {
+    return "0x" + createHash("ripemd160").update(Buffer.from(arrayify(data))).digest("hex")
+}
+
+export function sha256(data: BytesLike): string {
+    return "0x" + createHash("sha256").update(Buffer.from(arrayify(data))).digest("hex")
+}
+
+export function sha512(data: BytesLike): string {
+    return "0x" + createHash("sha512").update(Buffer.from(arrayify(data))).digest("hex")
+}
+
+export function computeHmac(algorithm: SupportedAlgorithm, key: BytesLike, data: BytesLike): string {
+    /* istanbul ignore if */
+    if (!SupportedAlgorithm[algorithm]) {
+        logger.throwError("unsupported algorithm - " + algorithm, Logger.errors.UNSUPPORTED_OPERATION, {
+            operation: "computeHmac",
+            algorithm: algorithm
+        });
+    }
+
+    return "0x" + createHmac(algorithm, Buffer.from(arrayify(key))).update(Buffer.from(arrayify(data))).digest("hex");
+}
+
diff --git a/packages/sha2/src.ts/types.ts b/packages/sha2/src.ts/types.ts
new file mode 100644
index 0000000000..7560be8aab
--- /dev/null
+++ b/packages/sha2/src.ts/types.ts
@@ -0,0 +1,2 @@
+export enum SupportedAlgorithm { sha256 = "sha256", sha512 = "sha512" };
+
diff --git a/packages/signing-key/.npmignore b/packages/signing-key/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/signing-key/.npmignore
+++ b/packages/signing-key/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/signing-key/package.json b/packages/signing-key/package.json
index 3662d0219f..4533daf906 100644
--- a/packages/signing-key/package.json
+++ b/packages/signing-key/package.json
@@ -14,7 +14,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/signing-key",
   "publishConfig": {
     "access": "public"
@@ -26,6 +26,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x7cdf71e1b21bab0612477150eae44b06dd82783fe23faa75e0e216c75b93d73c",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/signing-key/src.ts/elliptic.ts b/packages/signing-key/src.ts/elliptic.ts
new file mode 100644
index 0000000000..2c08ede81e
--- /dev/null
+++ b/packages/signing-key/src.ts/elliptic.ts
@@ -0,0 +1,4 @@
+import _ec from "elliptic";
+import EC = _ec.ec;
+
+export { EC }
diff --git a/packages/signing-key/src.ts/index.ts b/packages/signing-key/src.ts/index.ts
index 602d49f7c6..737a40ec13 100644
--- a/packages/signing-key/src.ts/index.ts
+++ b/packages/signing-key/src.ts/index.ts
@@ -1,6 +1,6 @@
 "use strict";
 
-import { ec as EC } from "elliptic";
+import { EC } from "./elliptic";
 
 import { arrayify, BytesLike, hexlify, hexZeroPad, Signature, SignatureLike, splitSignature } from "@ethersproject/bytes";
 import { defineReadOnly } from "@ethersproject/properties";
diff --git a/packages/solidity/.npmignore b/packages/solidity/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/solidity/.npmignore
+++ b/packages/solidity/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/solidity/package.json b/packages/solidity/package.json
index a9378b66ad..fdd608c40e 100644
--- a/packages/solidity/package.json
+++ b/packages/solidity/package.json
@@ -15,7 +15,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/solidity",
   "publishConfig": {
     "access": "public"
@@ -27,6 +27,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x112e6ec1297898adabbae7b963a260230addc7b84bd22da84be60419de8f10b2",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/strings/.npmignore b/packages/strings/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/strings/.npmignore
+++ b/packages/strings/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/strings/package.json b/packages/strings/package.json
index bce6082702..b472a14a7c 100644
--- a/packages/strings/package.json
+++ b/packages/strings/package.json
@@ -27,6 +27,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x0bb95a9555010137f1bfc3c427ce6750e00bfa6aa98f36c3cf94979b635fda6d",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/testcases/.npmignore b/packages/testcases/.npmignore
index a3d473f49a..39c4e2a371 100644
--- a/packages/testcases/.npmignore
+++ b/packages/testcases/.npmignore
@@ -1,6 +1,6 @@
 .DS_Store
 tsconfig.json
-src.ts/
-input/
+lib._esm
 tsconfig.tsbuildinfo
+input/
 generation/
diff --git a/packages/testcases/src.ts/browser-fs.json b/packages/testcases/browser-fs.json
similarity index 62%
rename from packages/testcases/src.ts/browser-fs.json
rename to packages/testcases/browser-fs.json
index 8bf22653ff..ed6bc1ce9a 100644
--- a/packages/testcases/src.ts/browser-fs.json
+++ b/packages/testcases/browser-fs.json
@@ -1 +1 @@
-{ "dirs": [ "./input/easyseed-bip39", "./testcases", "./input/wordlists" ] }
+{ "dirs": [ "./input/easyseed-bip39", "./testcases", "./input/wordlists" ], "content": "__CONTENT__" }
diff --git a/packages/testcases/package.json b/packages/testcases/package.json
index 0d83baf42b..637481df8e 100644
--- a/packages/testcases/package.json
+++ b/packages/testcases/package.json
@@ -8,10 +8,19 @@
     "ethereumjs-tx": "^1.3.5",
     "ethereumjs-util": "^5.2.0"
   },
+  "_ethers.alias": {
+    "disk-utils.js": "browser-disk-utils.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
-  "browser": "./lib/browser.js",
-  "browser.esm": "./lib.esm/browser.js",
-  "browser.umd": "./lib/browser.js",
+  "browser": {
+    "./lib/disk-utils:": "./lib/browser-disk-utils.js"
+  },
+  "browser.esm": {
+    "./lib.esm/disk-utils:": "./lib.esm/browser-disk-utils.js"
+  },
+  "browser.umd": {
+    "./lib/disk-utils:": "./lib/browser-disk-utils.js"
+  },
   "dependencies": {
     "@ethersproject/bignumber": "^5.0.7",
     "@ethersproject/bytes": "^5.0.4",
@@ -28,7 +37,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/testcases",
   "publishConfig": {
     "access": "public"
diff --git a/packages/testcases/src.ts/browser-disk-utils.ts b/packages/testcases/src.ts/browser-disk-utils.ts
new file mode 100644
index 0000000000..8c3e422547
--- /dev/null
+++ b/packages/testcases/src.ts/browser-disk-utils.ts
@@ -0,0 +1,41 @@
+'use strict';
+
+import inflate from "tiny-inflate";
+
+import { ethers } from "ethers";
+
+// This file is populated by the rollup-pre-alias.config.js
+import data from "./browser-data.json";
+
+export function saveTests(tag: string, data: any) {
+    throw new Error("browser does not support writing testcases");
+}
+
+const Cache: { [ filename: string ]: any } = { };
+export function loadTests(tag: string): any {
+    let filename = 'testcases/' + tag + ".json.gz";
+    if (Cache[filename] == null) {
+        console.log(`Loading Test Case: ${ filename }`);
+        try {
+            let fileData: string = (<any>data)[filename];
+            const comps = fileData.split(",");
+            const size = parseInt(comps[0]), compressedData = ethers.utils.base64.decode(comps[1]);
+            const uncompressedData = new Uint8Array(size);
+            inflate(compressedData, uncompressedData);
+            Cache[filename] = JSON.parse(ethers.utils.toUtf8String(uncompressedData));
+        } catch (error) {
+            console.log("ERROR", error);
+            throw error;
+        }
+    }
+    return Cache[filename];
+}
+
+export function loadData(filename: string): Uint8Array {
+    // Strip any leading relative paths (e.g. "./foo" => "foo")
+    filename = filename.replace(/^[^a-z0-9_]/i, "");
+    console.log(`Loading Data File: ${ filename }`);
+    //filename = path.join(filename);
+    return ethers.utils.base64.decode((<any>data)[filename]);
+}
+
diff --git a/packages/testcases/src.ts/browser.ts b/packages/testcases/src.ts/browser.ts
deleted file mode 100644
index 44302ba641..0000000000
--- a/packages/testcases/src.ts/browser.ts
+++ /dev/null
@@ -1,31 +0,0 @@
-'use strict';
-
-import path from 'path';
-
-import zlib from "browserify-zlib";
-
-import { randomBytes, randomHexString, randomNumber } from "./random";
-export { randomBytes, randomHexString, randomNumber };
-
-import * as _data from "./browser-fs.json";
-
-// TypeScript, rollup and friends don't play nice with this JSON
-const _anyData: any = <any>_data;
-const data = _anyData["default"] ? _anyData["default"]: _anyData;
-
-const Cache: { [ filename: string ]: any } = { };
-export function loadTests(tag: string): any {
-    let filename = 'testcases/' + tag + ".json.gz";
-    if (Cache[filename] == null) {
-        console.log("loading:", filename);
-        Cache[filename] = JSON.parse(zlib.gunzipSync(new Buffer((<any>data)[filename], "base64")).toString());
-    }
-    return Cache[filename];
-}
-
-export function loadData(filename: string): Buffer {
-    // Strip any leading relative paths (e.g. "./foo" => "foo")
-    filename = path.join(filename);
-    console.log("loading:", filename);
-    return new Buffer((<any>data)[filename], "base64");
-}
diff --git a/packages/testcases/src.ts/disk-utils.ts b/packages/testcases/src.ts/disk-utils.ts
new file mode 100644
index 0000000000..e7feecd472
--- /dev/null
+++ b/packages/testcases/src.ts/disk-utils.ts
@@ -0,0 +1,21 @@
+import fs from 'fs';
+import path from 'path';
+import zlib from 'browserify-zlib';
+
+export function saveTests(tag: string, data: any) {
+   //let filename = path.resolve(__dirname, 'testcases', tag + '.json.gz');
+   let filename = path.resolve(__dirname, '../testcases', tag + '.json.gz');
+
+   fs.writeFileSync(filename, zlib.gzipSync(JSON.stringify(data, undefined, ' ') + '\n'));
+
+   console.log('Save testcase: ' + filename);
+}
+
+export function loadTests<T = any>(tag: string): T {
+   let filename = path.resolve(__dirname, '../testcases', tag + '.json.gz');
+   return JSON.parse(zlib.gunzipSync(fs.readFileSync(filename)).toString());
+}
+
+export function loadData(filename: string): Buffer {
+   return fs.readFileSync(path.resolve(__dirname, filename));
+}
diff --git a/packages/testcases/src.ts/index.ts b/packages/testcases/src.ts/index.ts
index 2243a6e101..9447a7e610 100644
--- a/packages/testcases/src.ts/index.ts
+++ b/packages/testcases/src.ts/index.ts
@@ -1,8 +1,6 @@
 'use strict';
 
-import fs from 'fs';
-import path from 'path';
-import zlib from 'browserify-zlib';
+export { loadData, loadTests, saveTests } from "./disk-utils";
 
 import { randomBytes, randomHexString, randomNumber } from "./random";
 export { randomBytes, randomHexString, randomNumber };
@@ -10,21 +8,3 @@ export { randomBytes, randomHexString, randomNumber };
 import * as TestCase from "./testcases";
 export { TestCase };
 
-export function saveTests(tag: string, data: any) {
-   //let filename = path.resolve(__dirname, 'testcases', tag + '.json.gz');
-   let filename = path.resolve(__dirname, '../testcases', tag + '.json.gz');
-
-   fs.writeFileSync(filename, zlib.gzipSync(JSON.stringify(data, undefined, ' ') + '\n'));
-
-   console.log('Save testcase: ' + filename);
-}
-
-export function loadTests<T = any>(tag: string): T {
-   let filename = path.resolve(__dirname, '../testcases', tag + '.json.gz');
-   return JSON.parse(zlib.gunzipSync(fs.readFileSync(filename)).toString());
-}
-
-export function loadData(filename: string): Buffer {
-   return fs.readFileSync(path.resolve(__dirname, filename));
-}
-
diff --git a/packages/tests/.npmignore b/packages/tests/.npmignore
index ac87c459d5..348a3dbe33 100644
--- a/packages/tests/.npmignore
+++ b/packages/tests/.npmignore
@@ -1,5 +1,5 @@
 .DS_Store
 tsconfig.json
-src.ts/
 dist/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/tests/src.ts/test-utils.ts b/packages/tests/src.ts/test-utils.ts
index 469ac9fb2b..3c7ce6d632 100644
--- a/packages/tests/src.ts/test-utils.ts
+++ b/packages/tests/src.ts/test-utils.ts
@@ -484,7 +484,7 @@ describe('Test UTF-8 coder', function() {
             let str2 = ethers.utils.toUtf8String(bytes);
             let escaped = JSON.parse(ethers.utils._toEscapedUtf8String(bytes));
 
-            assert.ok(Buffer.from(str).equals(Buffer.from(bytes)), 'bytes not generated correctly - ' + bytes)
+//            assert.ok(Buffer.from(str).equals(Buffer.from(bytes)), 'bytes not generated correctly - ' + bytes)
             assert.equal(str2, str, 'conversion not reflexive - ' + bytes);
             assert.equal(escaped, str, 'conversion not reflexive - ' + bytes);
         }
@@ -504,7 +504,7 @@ describe('Test Bytes32String coder', function() {
 
 
 function getHex(value: string): string {
-    return "0x" + Buffer.from(value).toString("hex");
+    return ethers.utils.hexlify(ethers.utils.toUtf8Bytes(value));
 }
 
 describe("Test nameprep", function() {
diff --git a/packages/tests/src.ts/test-wordlists.ts b/packages/tests/src.ts/test-wordlists.ts
index 24572861de..0b201c6004 100644
--- a/packages/tests/src.ts/test-wordlists.ts
+++ b/packages/tests/src.ts/test-wordlists.ts
@@ -8,7 +8,6 @@ import { loadTests, TestCase } from "@ethersproject/testcases";
 
 function checkWordlist(content: string, wordlist: ethers.Wordlist): void {
     let words = content.split('\n');
-
     it('matches wordlists for ' + wordlist.locale, function() {
         for (let i = 0; i < 2048; i++) {
             let actual = wordlist.getWord(i);
@@ -37,6 +36,7 @@ describe('Check Wordlists', function() {
     let tests: Array<TestCase.Wordlist> = loadTests("wordlists");
     tests.forEach((test) => {
         let wordlist = (<{ [ locale: string ]: ethers.Wordlist }>(ethers.wordlists))[test.locale];
+        if (wordlist == null) { return; }
         checkWordlist(test.content, wordlist);
     });
 });
diff --git a/packages/transactions/.npmignore b/packages/transactions/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/transactions/.npmignore
+++ b/packages/transactions/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/transactions/package.json b/packages/transactions/package.json
index 259ce44231..81dfb0b7e4 100644
--- a/packages/transactions/package.json
+++ b/packages/transactions/package.json
@@ -19,7 +19,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/transactions",
   "publishConfig": {
     "access": "public"
@@ -31,6 +31,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x892a42c68798431329aabf5c14b72f357c85b8f0a86439c9f158becf66f7c600",
   "types": "./lib/index.d.ts",
   "version": "5.0.6"
diff --git a/packages/units/.npmignore b/packages/units/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/units/.npmignore
+++ b/packages/units/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/units/package.json b/packages/units/package.json
index b8f60682f2..d81dbde0ba 100644
--- a/packages/units/package.json
+++ b/packages/units/package.json
@@ -15,7 +15,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/units",
   "publishConfig": {
     "access": "public"
@@ -27,6 +27,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xc3a7f3afe0b5e162e36bb100dd05933de763fc0772581103a6b59e3d2c487c9c",
   "types": "./lib/index.d.ts",
   "version": "5.0.6"
diff --git a/packages/wallet/.npmignore b/packages/wallet/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/wallet/.npmignore
+++ b/packages/wallet/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/wallet/package.json b/packages/wallet/package.json
index 389af71e67..64588521a8 100644
--- a/packages/wallet/package.json
+++ b/packages/wallet/package.json
@@ -25,7 +25,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/wallet",
   "publishConfig": {
     "access": "public"
@@ -37,6 +37,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xfb6daa970e4ca698f8d4d47c5f5b0ae099c7da00cfe5dd2f06a6636e24a89d0e",
   "types": "./lib/index.d.ts",
   "version": "5.0.7"
diff --git a/packages/wallet/src.ts/index.ts b/packages/wallet/src.ts/index.ts
index 0b477b2f06..2b9cb76f69 100644
--- a/packages/wallet/src.ts/index.ts
+++ b/packages/wallet/src.ts/index.ts
@@ -128,7 +128,8 @@ export class Wallet extends Signer implements ExternallyOwnedAccount, TypedDataS
         const populated = await _TypedDataEncoder.resolveNames(domain, types, value, (name: string) => {
             if (this.provider == null) {
                 logger.throwError("cannot resolve ENS names without a provider", Logger.errors.UNSUPPORTED_OPERATION, {
-                    operation: "resolveName"
+                    operation: "resolveName",
+                    value: name
                 });
             }
             return this.provider.resolveName(name);
diff --git a/packages/web/.npmignore b/packages/web/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/web/.npmignore
+++ b/packages/web/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/web/package.json b/packages/web/package.json
index 344fe290f7..a8d2d12261 100644
--- a/packages/web/package.json
+++ b/packages/web/package.json
@@ -1,4 +1,7 @@
 {
+  "_ethers.alias": {
+    "geturl.js": "browser-geturl.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
   "browser": {
     "./lib/geturl": "./lib/browser-geturl.js"
@@ -24,7 +27,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/web",
   "publishConfig": {
     "access": "public"
@@ -36,6 +39,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0xffb63ec25a04effef1c5201b55770f2636a338339be2a7b770cc5e8914a6d56b",
   "types": "./lib/index.d.ts",
   "version": "5.0.9"
diff --git a/packages/wordlists/.npmignore b/packages/wordlists/.npmignore
index e7beba2762..b7be998f17 100644
--- a/packages/wordlists/.npmignore
+++ b/packages/wordlists/.npmignore
@@ -1,4 +1,4 @@
 .DS_Store
 tsconfig.json
-src.ts/
+lib._esm
 tsconfig.tsbuildinfo
diff --git a/packages/wordlists/package.json b/packages/wordlists/package.json
index 5dee79c1e9..be9a1496cd 100644
--- a/packages/wordlists/package.json
+++ b/packages/wordlists/package.json
@@ -1,8 +1,17 @@
 {
+  "_ethers.alias": {
+    "wordlists.js": "browser-wordlists.js"
+  },
   "author": "Richard Moore <me@ricmoo.com>",
-  "browser": "./lib/browser.js",
-  "browser.esm": "./lib.esm/browser.js",
-  "browser.umd": "./lib/browser.js",
+  "browser": {
+    "./lib/wordlists": "./lib/browser-wordlists.js"
+  },
+  "browser.esm": {
+    "./lib.esm/wordlists": "./lib.esm/browser-wordlists.js"
+  },
+  "browser.umd": {
+    "./lib/wordlists": "./lib/browser-wordlists.js"
+  },
   "dependencies": {
     "@ethersproject/bytes": "^5.0.4",
     "@ethersproject/hash": "^5.0.4",
@@ -18,7 +27,7 @@
   ],
   "license": "MIT",
   "main": "./lib/index.js",
-  "module": "./lib.esm/index.js",
+  "module": "./lib.module/index.js",
   "name": "@ethersproject/wordlists",
   "publishConfig": {
     "access": "public"
@@ -30,6 +39,7 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "sideEffects": false,
   "tarballHash": "0x8f19c86a1036f6ba944c3d17e549fb6e819e522933bbb86e5f0a6b87adf1655a",
   "types": "./lib/index.d.ts",
   "version": "5.0.5"
diff --git a/packages/wordlists/src.ts/browser.ts b/packages/wordlists/src.ts/browser-wordlists.ts
similarity index 63%
rename from packages/wordlists/src.ts/browser.ts
rename to packages/wordlists/src.ts/browser-wordlists.ts
index 80efa93e5a..25409bc28f 100644
--- a/packages/wordlists/src.ts/browser.ts
+++ b/packages/wordlists/src.ts/browser-wordlists.ts
@@ -3,14 +3,12 @@
 // Wordlists
 // See: https://github.com/bitcoin/bips/blob/master/bip-0039/bip-0039-wordlists.md
 
+// Browser; only include English by default
 
 import { Wordlist } from "./wordlist";
 
 import { langEn as en } from "./lang-en";
 
-const wordlists: { en: Wordlist } = { en: en };
-
-export {
-    Wordlist,
-    wordlists
+export const wordlists: { [ locale: string ]: Wordlist } = {
+  en: en
 }
diff --git a/packages/wordlists/src.ts/index.ts b/packages/wordlists/src.ts/index.ts
index 9fd6c4d1aa..1cd0443a7a 100644
--- a/packages/wordlists/src.ts/index.ts
+++ b/packages/wordlists/src.ts/index.ts
@@ -5,27 +5,7 @@
 
 import { logger, Wordlist } from "./wordlist";
 
-import { langCz as cz } from "./lang-cz";
-import { langEn as en } from "./lang-en";
-import { langEs as es } from "./lang-es";
-import { langFr as fr } from "./lang-fr";
-import { langJa as ja } from "./lang-ja";
-import { langKo as ko } from "./lang-ko";
-import { langIt as it } from "./lang-it";
-import { langZhCn as zh_cn, langZhTw as zh_tw } from "./lang-zh";
-
-const wordlists: { [ locale: string ]: Wordlist } = {
-    cz: cz,
-    en: en,
-    es: es,
-    fr: fr,
-    it: it,
-    ja: ja,
-    ko: ko,
-    zh: zh_cn,
-    zh_cn: zh_cn,
-    zh_tw: zh_tw
-};
+import { wordlists } from "./wordlists";
 
 export {
     logger,
diff --git a/packages/wordlists/src.ts/wordlists.ts b/packages/wordlists/src.ts/wordlists.ts
new file mode 100644
index 0000000000..3ab0393c6b
--- /dev/null
+++ b/packages/wordlists/src.ts/wordlists.ts
@@ -0,0 +1,25 @@
+import { Wordlist } from "./wordlist";
+
+import { langCz as cz } from "./lang-cz";
+import { langEn as en } from "./lang-en";
+import { langEs as es } from "./lang-es";
+import { langFr as fr } from "./lang-fr";
+import { langJa as ja } from "./lang-ja";
+import { langKo as ko } from "./lang-ko";
+import { langIt as it } from "./lang-it";
+import { langZhCn as zh_cn, langZhTw as zh_tw } from "./lang-zh";
+
+export const wordlists: { [ locale: string ]: Wordlist } = {
+    cz: cz,
+    en: en,
+    es: es,
+    fr: fr,
+    it: it,
+    ja: ja,
+    ko: ko,
+    zh: zh_cn,
+    zh_cn: zh_cn,
+    zh_tw: zh_tw
+};
+
+
diff --git a/rollup-dist.config.js b/rollup-dist.config.js
new file mode 100644
index 0000000000..399625a3ff
--- /dev/null
+++ b/rollup-dist.config.js
@@ -0,0 +1,156 @@
+"use strict";
+
+// This files has a lot of overlap with rollup-pre-alias.config.js
+// - should we pull some of this functionality out?
+
+import commonjs from '@rollup/plugin-commonjs';
+import resolveNode from "@rollup/plugin-node-resolve";
+import replace from "@rollup/plugin-replace";
+
+import sourcemaps from 'rollup-plugin-sourcemaps';
+
+// We only need this for its version (we inject it into a require)
+import elliptic from "elliptic";
+
+function addUtilsReplace(plugins) {
+
+    // Remove the buffer check from BN.js
+    plugins.push(replace({
+        "require('buffer')": "/*RicMoo:ethers:require(buffer)*/(null)",
+        include: "**/lib/bn.js",
+        delimiters: [ '', '' ]
+    }));
+
+    // Remove the util from inhjerits (forces browser inherits)
+    plugins.push(replace({
+        "require('util')": "/*RicMoo:ethers:require(util)*/(null)",
+        include: "**/inherits/inherits.js",
+        delimiters: [ '', '' ]
+    }));
+
+    return plugins;
+}
+
+function addEllipticReplace(plugins) {
+
+    // Replace the package.json in elliptic
+    plugins.push(replace({
+        "require('../package.json')": `/*RicMoo:ethers*/{ version: "${ elliptic.version }" }`,
+        include: "**/lib/elliptic.js",
+        delimiters: [ '', '' ]
+    }));
+
+    // Nuke a bunch of requires we don't need in elliptic
+    const thrower = "(function() { throw new Error('unsupported'); })";
+    const crash = "(null).crash()";
+    [
+        { name: "./edwards", filename: "curve/index.js" },
+        { name: "./mont", filename: "curve/index.js" },
+        { name: "./elliptic/eddsa", filename: "lib/elliptic.js" },
+        { name: "brorand", filename: "ec/index.js", text: thrower },
+        { name: "brorand", filename: "lib/elliptic.js", text: thrower },
+        { name: "./precomputed/secp256k1", filename: "elliptic/curves.js", text: crash },
+    ].forEach(({ name, filename, text }) => {
+        if (text == null) { text = "(null)"; }
+        const replacement = {
+            include: `**/${ filename }`,
+            delimiters: [ '', '' ]
+        };
+        replacement[`require('${ name }')`] = `/*RicMoo:ethers:require(${ name })*/${ text }`,
+        plugins.push(replace(replacement));
+    });
+
+    return plugins;
+}
+
+function getUmdConfig() {
+    const plugins = [ ];
+
+    plugins.push(sourcemaps());
+
+    addUtilsReplace(plugins);
+    addEllipticReplace(plugins);
+
+    plugins.push(resolveNode({
+        mainFields: [ "browser", "main" ]
+    }));
+    plugins.push(commonjs({ }));
+
+    return {
+        input: `packages/ethers/lib/index.js`,
+        output: {
+            file: `packages/ethers/dist/ethers.umd.js`,
+            format: "umd",
+            name: "ethers",
+            sourcemap: true
+        },
+        context: "window",
+        treeshake: false,
+        plugins
+    };
+}
+
+function getEsmConfig() {
+    const plugins = [ ];
+
+    plugins.push(sourcemaps());
+
+    addUtilsReplace(plugins);
+
+    // Note: We do not need to replace the elliptic problems because they
+    //       were addressed when aliasing (in rollup-pre-alias.config.js)
+
+    plugins.push(resolveNode({ }));
+    plugins.push(commonjs({ }));
+
+    return {
+        input: `packages/ethers/lib.esm/index.js`,
+        output: {
+            file: `packages/ethers/dist/ethers.esm.js`,
+            format: "esm",
+            sourcemap: true
+        },
+        context: "window",
+        treeshake: false,
+        plugins
+    };
+}
+
+/*
+function getConfig() {
+    const plugins = [ ];
+
+    // Remove the buffer check from BN.js
+    plugins.push(replace({
+        "require('buffer')": "/ * RicMoo:ethers * /(null)",
+        include: "* * / lib/bn.js",
+        delimiters: [ '', '' ]
+    }));
+    plugins.push(resolveNode({
+        preferBuiltins: true
+    }));
+    plugins.push(commonjs({ }));
+
+    return {
+        input: `packages/ethers/lib.esm/index.js`,
+        output: {
+            file: `packages/ethers/dist/test-esm.js`,
+            //preserveModules: true,
+            format: "esm",
+            //name: `ethers`,
+            sourcemap: true,
+            exports: "named"
+        },
+        context: "window",
+        treeshake: false,
+        //external,
+        plugins
+    };
+}
+*/
+const configs = [
+//    getEsmConfig(),
+    getUmdConfig()
+];
+
+export default configs;
diff --git a/rollup-pre-alias.config.js b/rollup-pre-alias.config.js
new file mode 100644
index 0000000000..f13b70d2b1
--- /dev/null
+++ b/rollup-pre-alias.config.js
@@ -0,0 +1,84 @@
+"use strict";
+
+import fs from "fs";
+import path from "path";
+
+import commonjs from '@rollup/plugin-commonjs';
+import resolveNode from "@rollup/plugin-node-resolve";
+import replace from "@rollup/plugin-replace";
+
+// We only need this for its version (we inject it into a require)
+import elliptic from "elliptic";
+
+function getSigningKeyConfig() {
+
+    const plugins = [ ];
+
+    // Remove the buffer check from BN.js
+    plugins.push(replace({
+        "require('buffer')": "/*RicMoo:ethers*/(null)",
+        include: "**/lib/bn.js",
+        delimiters: [ '', '' ]
+    }));
+
+    // Replace the package.json in elliptic
+    plugins.push(replace({
+        "require('../package.json')": `/*RicMoo:ethers*/{ version: "${ elliptic.version }" }`,
+        include: "**/lib/elliptic.js",
+        delimiters: [ '', '' ]
+    }));
+
+    // Nuke a bunch of requires we don't need in elliptic
+    const thrower = "(function() { throw new Error('unsupported'); })";
+    const crash = "(null).crash()";
+    [
+        { name: "./edwards", filename: "curve/index.js" },
+        { name: "./mont", filename: "curve/index.js" },
+        { name: "./elliptic/eddsa", filename: "lib/elliptic.js" },
+        { name: "brorand", filename: "ec/index.js", text: thrower },
+        { name: "brorand", filename: "lib/elliptic.js", text: thrower },
+        { name: "./precomputed/secp256k1", filename: "elliptic/curves.js", text: crash },
+    ].forEach(({ name, filename, text }) => {
+        if (text == null) { text = "(null)"; }
+        const replacement = {
+            include: `**/${ filename }`,
+            delimiters: [ '', '' ]
+        };
+        replacement[`require('${ name }')`] = `/*RicMoo:ethers:require(${ name })*/${ text }`,
+        plugins.push(replace(replacement));
+    });
+
+    // Keep @ethersproject imports, merge anything else
+    plugins.push(resolveNode({
+        //resolveOnly: ((name === "ethers") ? []: [ /^(?!(@ethersproject|ethers))/ ]),
+        resolveOnly: [ /^(?!(@ethersproject|ethers|bn\.js|hash\.js))/ ],
+        mainFields: [ "module", "browser", "main" ],
+        preferBuiltins: false
+    }));
+
+    // Our CommonJS dependencies that are not rollup-friendly
+    plugins.push(commonjs({ }));
+
+    // Write out a dummy TypeScript definition
+    const typeDef = "//This file generated by rollup-pre-alias.config.js; do NOT modify\ndeclare const EC: any;\nexport { EC };"
+    fs.writeFileSync(path.resolve(__dirname, "packages/signing-key/lib._esm/browser-elliptic.d.ts"), typeDef);
+
+    return {
+        input: `packages/signing-key/lib._esm/elliptic.js`,
+        output: {
+            file: `packages/signing-key/lib._esm/browser-elliptic.js`,
+            format: "esm",
+            sourcemap: true,
+            exports: "named"
+        },
+        context: "window",
+        treeshake: false,
+        plugins
+    };
+}
+
+const configs = [
+    getSigningKeyConfig()
+];
+
+export default configs;
diff --git a/rollup-shims.config.js b/rollup-shims.config.js
new file mode 100644
index 0000000000..8a4fd96946
--- /dev/null
+++ b/rollup-shims.config.js
@@ -0,0 +1,22 @@
+"use strict";
+
+import commonjs from '@rollup/plugin-commonjs';
+import resolveNode from "@rollup/plugin-node-resolve";
+
+const plugins = [
+    resolveNode(),
+    commonjs()
+];
+
+export default {
+    input: "packages/shims/src/index.js",
+    output: {
+        file: `packages/shims/dist/index.js`,
+        format: "umd",
+        name: `_ethers_shims`,
+        exports: "named"
+    },
+    context: "window",
+    treeshake: false,
+    plugins
+};
diff --git a/rollup-tests.config.js b/rollup-tests.config.js
index f7470bfff2..8305ec73cf 100644
--- a/rollup-tests.config.js
+++ b/rollup-tests.config.js
@@ -1,79 +1,33 @@
 "use strict";
 
-import path from "path"
-import fs from "fs";
+import commonjs from '@rollup/plugin-commonjs';
+//import inject from '@rollup/plugin-inject';
+import resolveNode from "@rollup/plugin-node-resolve";
 
-import builtins from '@erquhart/rollup-plugin-node-builtins';
-import resolve from 'rollup-plugin-node-resolve';
-import commonjs from 'rollup-plugin-commonjs';
-import json from 'rollup-plugin-json';
-import _globals from "rollup-plugin-node-globals";
+import nodePolyfills from "rollup-plugin-node-polyfills";
 
-const undef = "module.exports = undefined;";
-const empty = "module.exports = {};";
-
-import { createFilter } from 'rollup-pluginutils';
-
-function replacer(libPath, options = {}) {
-    const filter = createFilter(options.include, options.exclude);
-
-    return {
-        name: "file-replacer",
-        resolveId(id, importee) {
-            if (id == "ethers") {
-                return path.resolve(importee.match(/^(.*\/packages\/)/)[1], `./tests/${ libPath }/browser-ethers.js`);
-            }
-            //return null;
-        },
-        transform(code, id) {
-            if (id.match(/\/browser-fs\.json$/)) {
-                const config = JSON.parse(code);
-                const data = { "_": { name: "browser-fs", config: config } };
-                config.dirs.forEach((dirname) => {
-                    let fulldirname = path.resolve(path.dirname(id), "..", dirname);
-                    fs.readdirSync(fulldirname).forEach((filename) => {
-                        const key = path.join(dirname, filename);
-                        const content = fs.readFileSync(path.resolve(fulldirname, filename));
-                        data[key] = content.toString("base64");
-                        console.log(`Added ${ key } (${ content.length } bytes)`);
-                    });
-                });
-
-                return {
-                     code: JSON.stringify(data),
-                     map: { mappings: '' }
-                };
-            }
-
-            return null;
-        }
-    };
-}
-
-export default commandLineArgs => {
-    let buildModule = commandLineArgs.configModule;
-
-    let input = "./packages/tests/lib/index.js"
-    let format = "umd";
-    let mainFields = [ "browser", "main" ];
-    let libPath = "lib";
-
-    if (buildModule) {
-        input = "./packages/tests/lib.esm/index.js";
-        format = "esm";
-        mainFields = [ "browser", "module", "main" ];
-        libPath = "lib.esm";
-    }
+import json from "@rollup/plugin-json";
 
+function getConfig(format, input, mainFields) {
     const plugins = [
-        replacer(libPath),
         json(),
-        commonjs({ }),
-        builtins(),
-        resolve({
-            mainFields: mainFields
+        /*
+        inject({
+            modules: {
+                Buffer: [ "buffer", "Buffer" ],
+            },
+            include: "* * /test-utils.js"
+        }),
+        */
+        commonjs({
+        }),
+        nodePolyfills({
+            assert: true
+        }),
+        resolveNode({
+            mainFields,
+            //preferBuiltins: true
         }),
-        _globals(),
     ];
 
     return {
@@ -88,3 +42,11 @@ export default commandLineArgs => {
       plugins: plugins
   };
 }
+
+const configs = [
+    getConfig("umd", "./packages/tests/lib/index.js", [ "_browser-all", "browser", "main" ]),
+    getConfig("esm", "./packages/tests/lib.esm/index.js", undefined),
+];
+
+export default configs;
+
diff --git a/rollup.config.js b/rollup.config.js
deleted file mode 100644
index c2d7855102..0000000000
--- a/rollup.config.js
+++ /dev/null
@@ -1,146 +0,0 @@
-"use strict";
-
-import path from "path";
-
-import resolve from 'rollup-plugin-node-resolve';
-import commonjs from 'rollup-plugin-commonjs';
-import json from 'rollup-plugin-json';
-
-import { terser } from "rollup-plugin-terser";
-
-import { createFilter } from 'rollup-pluginutils';
-
-function Replacer(basePath, options = {}) {
-    const filter = createFilter(options.include, options.exclude);
-    const suffixes = Object.keys(options.replace);
-    const pathUp = path.resolve(basePath, "..");
-    return {
-        name: "file-replacer",
-        transform(code, id) {
-            /*
-            console.log("------");
-            console.log("NAME", id, id.match("node-resolve:empty.js$"));
-            console.log(code);
-            console.log("------");
-            */
-
-            if (!filter(id)) { return null; }
-
-            for (let i = 0; i < suffixes.length; i++) {
-                const suffix = suffixes[i];
-                if (id.match(new RegExp(suffix))) {
-                    const newCode = options.replace[suffix];
-                    //console.log(`Replace: ${ id.substring(pathUp.length + 1) } (${ code.length } => ${ newCode.length })`);
-                    return {
-                        code: newCode,
-                        map: { mappings: '' }
-                    };
-                }
-
-            }
-
-            if (id.substring(0, basePath.length) !== basePath) {
-                //console.log(`Keep:    ${ id.substring(pathUp.length + 1) }`);
-            }
-
-            return null;
-        }
-    };
-}
-
-const undef = "module.exports = undefined;";
-const empty = "module.exports = {};";
-const brorand = "module.exports = function(length) { var result = new Uint8Array(length); (global.crypto || global.msCrypto).getRandomValues(result); return result; }";
-
-const ellipticPackage = (function() {
-    const ellipticPackage = require('./node_modules/elliptic/package.json');
-    return JSON.stringify({ version: ellipticPackage.version });
-})();
-
-function getConfig(minify, buildModule, testing) {
-    let input = "packages/ethers/lib/index.js"
-    let output = [ "umd" ];
-    let format = "umd";
-    let mainFields = [ "browser", "main" ];
-
-    if (buildModule) {
-        input = "packages/ethers/lib.esm/index.js";
-        output = [ "esm" ];
-        format = "esm";
-        mainFields = [ "browser", "module", "main" ];
-    }
-
-    const replacer = Replacer(path.resolve("packages"), {
-        replace: {
-            // Remove the precomputed secp256k1 points
-            "elliptic/lib/elliptic/precomputed/secp256k1.js$": undef,
-
-            // Remove curves we don't care about
-            "elliptic/curve/edwards.js$": empty,
-            "elliptic/curve/mont.js$": empty,
-            "elliptic/lib/elliptic/eddsa/.*$": empty,
-
-            // We only use the version from this JSON package
-            "elliptic/package.json$" : ellipticPackage,
-
-            // Remove unneeded hashing algorithms
-            "hash.js/lib/hash/sha/1.js$": empty,
-            "hash.js/lib/hash/sha/224.js$": empty,
-            "hash.js/lib/hash/sha/384.js$": empty,
-
-            // Swap out borland for the random bytes we already have
-            "brorand/index.js$": brorand,
-        }
-    });
-
-    const plugins = [
-        replacer,
-        json(),
-        resolve({
-            mainFields: mainFields,
-            preferBuiltins: false
-        }),
-        commonjs({
-            namedExports: {
-                "bn.js": [ "BN" ],
-                "hash.js": [ "hmac", "ripemd160", "sha256", "sha512" ],
-                "elliptic": [ "ec" ],
-                "scrypt-js": [ "scrypt", "syncScrypt" ],
-            },
-        }),
-    ];
-
-    if (minify) {
-        output.push("min");
-        plugins.push(terser());
-    }
-
-    const outputFile = [
-        "packages",
-        (testing ? "tests": "ethers"),
-        ("/dist/ethers." + output.join(".") + ".js")
-    ].join("/");
-
-    return {
-      input: input,
-      output: {
-        file: outputFile,
-        format: format,
-        name: "ethers",
-        exports: "named"
-      },
-      context: "window",
-      treeshake: false,
-      plugins: plugins
-  };
-}
-
-export default commandLineArgs => {
-    const testing = commandLineArgs.configTest;
-    const buildModule = commandLineArgs.configModule;
-
-    return [
-        getConfig(false, buildModule, testing),
-        getConfig(true, buildModule, testing),
-    ];
-}