diff --git a/.github/workflows/web.yml b/.github/workflows/web.yml
index 1ee20b0..579c541 100644
--- a/.github/workflows/web.yml
+++ b/.github/workflows/web.yml
@@ -17,10 +17,20 @@ jobs:
           cache: 'npm'
           cache-dependency-path: viewer/package-lock.json
 
+      - name: Install wasm-pack
+        uses: jetli/wasm-pack-action@v0.4.0
+
+      - name: Cache WASM build
+        uses: actions/cache@v3
+        with:
+          path: target
+          key: doesnt-matter-share-everything
+
       - name: Build web app
         run: |
           cd viewer
           npm ci
+          npm run wasm
           npm run build --if-present
 
       - name: Publish
diff --git a/Cargo.lock b/Cargo.lock
index 3332776..1d95e62 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -140,6 +140,12 @@ version = "2.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "630be753d4e58660abd17930c71b647fe46c27ea6b63cc59e1e3851406972e42"
 
+[[package]]
+name = "bumpalo"
+version = "3.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a3e2c3daef883ecc1b5d58c15adae93470a91d425f3532ba1695849656af3fc1"
+
 [[package]]
 name = "byteorder"
 version = "1.4.3"
@@ -515,6 +521,15 @@ version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "af150ab688ff2122fcef229be89cb50dd66af9e01a4ff320cc137eecc9bacc38"
 
+[[package]]
+name = "js-sys"
+version = "0.3.64"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c5f195fe497f702db0f318b07fdd68edb16955aed830df8363d837542f8f935a"
+dependencies = [
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
@@ -558,6 +573,11 @@ checksum = "b06a4cde4c0f271a446782e3eff8de789548ce57dbc8eca9292c27f4a42004b4"
 [[package]]
 name = "lts"
 version = "0.1.0"
+dependencies = [
+ "serde",
+ "serde-wasm-bindgen",
+ "wasm-bindgen",
+]
 
 [[package]]
 name = "memchr"
@@ -855,6 +875,17 @@ dependencies = [
  "serde_derive",
 ]
 
+[[package]]
+name = "serde-wasm-bindgen"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3b143e2833c57ab9ad3ea280d21fd34e285a42837aeb0ee301f4f41890fa00e"
+dependencies = [
+ "js-sys",
+ "serde",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "serde_derive"
 version = "1.0.188"
@@ -966,6 +997,60 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "711b9620af191e0cdc7468a8d14e709c3dcdb115b36f838e601583af800a370a"
 
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7706a72ab36d8cb1f80ffbf0e071533974a60d0a308d01a5d0375bf60499a342"
+dependencies = [
+ "cfg-if",
+ "wasm-bindgen-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-backend"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ef2b6d3c510e9625e5fe6f509ab07d66a760f0885d858736483c32ed7809abd"
+dependencies = [
+ "bumpalo",
+ "log",
+ "once_cell",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dee495e55982a3bd48105a7b947fd2a9b4a8ae3010041b9e0faab3f9cd028f1d"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "54681b18a46765f095758388f2d0cf16eb8d4169b639ab575a8f5693af210c7b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-backend",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca6ad05a4870b2bf5fe995117d3728437bd27d7cd5f06f13c17443ef369775a1"
+
 [[package]]
 name = "which"
 version = "4.4.0"
diff --git a/lts/Cargo.toml b/lts/Cargo.toml
index 352cd01..ca9ad18 100644
--- a/lts/Cargo.toml
+++ b/lts/Cargo.toml
@@ -3,4 +3,10 @@ name = "lts"
 version = "0.1.0"
 edition = "2021"
 
-[dependencies]
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+serde = { version = "1.0.188", features = ["derive"] }
+serde-wasm-bindgen = "0.5.0"
+wasm-bindgen = "0.2.87"
diff --git a/lts/src/lib.rs b/lts/src/lib.rs
index 34df0c3..af37404 100644
--- a/lts/src/lib.rs
+++ b/lts/src/lib.rs
@@ -2,6 +2,8 @@ mod bike_ottawa;
 mod parse;
 mod speed_limit_only;
 mod tags;
+#[cfg(target_arch = "wasm32")]
+mod wasm;
 
 pub use bike_ottawa::bike_ottawa;
 pub use speed_limit_only::speed_limit_only;
diff --git a/lts/src/wasm.rs b/lts/src/wasm.rs
new file mode 100644
index 0000000..827e2b8
--- /dev/null
+++ b/lts/src/wasm.rs
@@ -0,0 +1,43 @@
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+use wasm_bindgen::prelude::*;
+
+use crate::{bike_ottawa, speed_limit_only, Tags, LTS};
+
+#[derive(Deserialize)]
+struct Input {
+    // TODO Improve this API
+    method: String,
+    tags: HashMap<String, String>,
+}
+
+#[derive(Serialize)]
+struct Output {
+    lts: usize,
+    messages: Vec<String>,
+}
+
+#[wasm_bindgen()]
+pub fn calculate(input: JsValue) -> Result<JsValue, JsValue> {
+    let input: Input = serde_wasm_bindgen::from_value(input)?;
+    let mut tags = Tags::new();
+    for (k, v) in input.tags {
+        tags.insert(k, v);
+    }
+
+    let (lts, messages) = if input.method == "speed_limit_only" {
+        speed_limit_only::speed_limit_only(tags)
+    } else if input.method == "bike_ottawa" {
+        bike_ottawa::bike_ottawa(tags)
+    } else {
+        (
+            LTS::NotAllowed,
+            vec![format!("Unknown method {}", input.method)],
+        )
+    };
+    let result = serde_wasm_bindgen::to_value(&Output {
+        lts: lts.into_json(),
+        messages,
+    })?;
+    Ok(result)
+}
diff --git a/viewer/package-lock.json b/viewer/package-lock.json
index dd80458..7d014da 100644
--- a/viewer/package-lock.json
+++ b/viewer/package-lock.json
@@ -23,7 +23,8 @@
         "svelte-check": "^3.4.4",
         "tslib": "^2.6.0",
         "typescript": "^5.1.3",
-        "vite": "^4.3.9"
+        "vite": "^4.3.9",
+        "vite-plugin-wasm-pack": "0.1.11"
       }
     },
     "node_modules/@ampproject/remapping": {
@@ -1470,6 +1471,20 @@
         "node": ">=8"
       }
     },
+    "node_modules/fs-extra": {
+      "version": "10.1.0",
+      "resolved": "https://registry.npmjs.org/fs-extra/-/fs-extra-10.1.0.tgz",
+      "integrity": "sha512-oRXApq54ETRj4eMiFzGnHWGy+zo5raudjuxN0b8H7s/RU2oW0Wvsx9O0ACRN/kRq9E8Vu/ReskGB5o3ji+FzHQ==",
+      "dev": true,
+      "dependencies": {
+        "graceful-fs": "^4.2.0",
+        "jsonfile": "^6.0.1",
+        "universalify": "^2.0.0"
+      },
+      "engines": {
+        "node": ">=12"
+      }
+    },
     "node_modules/fs.realpath": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
@@ -1778,6 +1793,18 @@
         "node": ">=6"
       }
     },
+    "node_modules/jsonfile": {
+      "version": "6.1.0",
+      "resolved": "https://registry.npmjs.org/jsonfile/-/jsonfile-6.1.0.tgz",
+      "integrity": "sha512-5dgndWOriYSm5cnYaJNhalLNDKOqFwyDB/rr1E9ZsGciGvKPs8R2xYGCacuf3z6K1YKDz182fd+fY3cn3pMqXQ==",
+      "dev": true,
+      "dependencies": {
+        "universalify": "^2.0.0"
+      },
+      "optionalDependencies": {
+        "graceful-fs": "^4.1.6"
+      }
+    },
     "node_modules/just-compare": {
       "version": "2.3.0",
       "resolved": "https://registry.npmjs.org/just-compare/-/just-compare-2.3.0.tgz",
@@ -1980,6 +2007,12 @@
         "node": "^10 || ^12 || ^13.7 || ^14 || >=15.0.1"
       }
     },
+    "node_modules/narrowing": {
+      "version": "1.5.0",
+      "resolved": "https://registry.npmjs.org/narrowing/-/narrowing-1.5.0.tgz",
+      "integrity": "sha512-DUu4XdKgkfAPTAL28k79pdnshDE2W5T24QAnidSPo2F/W1TX6CjNzmEeXQfE5O1lxQvC0GYI6ZRDsLcyzugEYA==",
+      "dev": true
+    },
     "node_modules/node-releases": {
       "version": "2.0.13",
       "resolved": "https://registry.npmjs.org/node-releases/-/node-releases-2.0.13.tgz",
@@ -2676,6 +2709,15 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/universalify": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/universalify/-/universalify-2.0.0.tgz",
+      "integrity": "sha512-hAZsKq7Yy11Zu1DE0OzWjw7nnLZmJZYTDZZyEFHZdUhV8FkH5MCfoU1XMaxXovpyW5nq5scPqq0ZDP9Zyl04oQ==",
+      "dev": true,
+      "engines": {
+        "node": ">= 10.0.0"
+      }
+    },
     "node_modules/update-browserslist-db": {
       "version": "1.0.11",
       "resolved": "https://registry.npmjs.org/update-browserslist-db/-/update-browserslist-db-1.0.11.tgz",
@@ -2761,6 +2803,87 @@
         }
       }
     },
+    "node_modules/vite-plugin-wasm-pack": {
+      "version": "0.1.11",
+      "resolved": "https://registry.npmjs.org/vite-plugin-wasm-pack/-/vite-plugin-wasm-pack-0.1.11.tgz",
+      "integrity": "sha512-eImq3bVNUXd2MAjz9WztqLSKabvWf6/7x2KDJdPYYqQncDOo7IqvuSvQiGW+8ihRgbI3uQuzqAL5AG4vAoHcEg==",
+      "dev": true,
+      "dependencies": {
+        "chalk": "^4.1.2",
+        "fs-extra": "^10.0.0",
+        "narrowing": "^1.4.0"
+      }
+    },
+    "node_modules/vite-plugin-wasm-pack/node_modules/ansi-styles": {
+      "version": "4.3.0",
+      "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-4.3.0.tgz",
+      "integrity": "sha512-zbB9rCJAT1rbjiVDb2hqKFHNYLxgtk8NURxZ3IZwD3F6NtxbXZQCnnSi1Lkx+IDohdPlFp222wVALIheZJQSEg==",
+      "dev": true,
+      "dependencies": {
+        "color-convert": "^2.0.1"
+      },
+      "engines": {
+        "node": ">=8"
+      },
+      "funding": {
+        "url": "https://github.com/chalk/ansi-styles?sponsor=1"
+      }
+    },
+    "node_modules/vite-plugin-wasm-pack/node_modules/chalk": {
+      "version": "4.1.2",
+      "resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
+      "integrity": "sha512-oKnbhFyRIXpUuez8iBMmyEa4nbj4IOQyuhc/wy9kY7/WVPcwIO9VA668Pu8RkO7+0G76SLROeyw9CpQ061i4mA==",
+      "dev": true,
+      "dependencies": {
+        "ansi-styles": "^4.1.0",
+        "supports-color": "^7.1.0"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "url": "https://github.com/chalk/chalk?sponsor=1"
+      }
+    },
+    "node_modules/vite-plugin-wasm-pack/node_modules/color-convert": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/color-convert/-/color-convert-2.0.1.tgz",
+      "integrity": "sha512-RRECPsj7iu/xb5oKYcsFHSppFNnsj/52OVTRKb4zP5onXwVF3zVmmToNcOfGC+CRDpfK/U584fMg38ZHCaElKQ==",
+      "dev": true,
+      "dependencies": {
+        "color-name": "~1.1.4"
+      },
+      "engines": {
+        "node": ">=7.0.0"
+      }
+    },
+    "node_modules/vite-plugin-wasm-pack/node_modules/color-name": {
+      "version": "1.1.4",
+      "resolved": "https://registry.npmjs.org/color-name/-/color-name-1.1.4.tgz",
+      "integrity": "sha512-dOy+3AuW3a2wNbZHIuMZpTcgjGuLU/uBL/ubcZF9OXbDo8ff4O8yVp5Bf0efS8uEoYo5q4Fx7dY9OgQGXgAsQA==",
+      "dev": true
+    },
+    "node_modules/vite-plugin-wasm-pack/node_modules/has-flag": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-4.0.0.tgz",
+      "integrity": "sha512-EykJT/Q1KjTWctppgIAgfSO0tKVuZUjhgMr17kqTumMl6Afv3EISleU7qZUzoXDFTAHTDC4NOoG/ZxU3EvlMPQ==",
+      "dev": true,
+      "engines": {
+        "node": ">=8"
+      }
+    },
+    "node_modules/vite-plugin-wasm-pack/node_modules/supports-color": {
+      "version": "7.2.0",
+      "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.2.0.tgz",
+      "integrity": "sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==",
+      "dev": true,
+      "dependencies": {
+        "has-flag": "^4.0.0"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
     "node_modules/vitefu": {
       "version": "0.2.4",
       "resolved": "https://registry.npmjs.org/vitefu/-/vitefu-0.2.4.tgz",
diff --git a/viewer/package.json b/viewer/package.json
index ce3019e..7dd9593 100644
--- a/viewer/package.json
+++ b/viewer/package.json
@@ -6,6 +6,7 @@
   "scripts": {
     "dev": "vite",
     "build": "vite build",
+    "wasm": "wasm-pack build --release --target web ../lts",
     "preview": "vite preview",
     "check": "svelte-check --tsconfig ./tsconfig.json",
     "fmt": "npx prettier --write *.html src/**"
@@ -21,7 +22,8 @@
     "svelte-check": "^3.4.4",
     "tslib": "^2.6.0",
     "typescript": "^5.1.3",
-    "vite": "^4.3.9"
+    "vite": "^4.3.9",
+    "vite-plugin-wasm-pack": "0.1.11"
   },
   "dependencies": {
     "@turf/bbox": "^6.5.0",
diff --git a/viewer/src/App.svelte b/viewer/src/App.svelte
index a29620d..48f9441 100644
--- a/viewer/src/App.svelte
+++ b/viewer/src/App.svelte
@@ -1,10 +1,12 @@
 <script lang="ts">
   import turfBbox from "@turf/bbox";
   import type { Feature, FeatureCollection } from "geojson";
+  import init from "lts";
   import type {
     DataDrivenPropertyValueSpecification,
     Map as MapType,
   } from "maplibre-gl";
+  import { onMount } from "svelte";
   import {
     CircleLayer,
     GeoJSON,
@@ -20,6 +22,10 @@
   import PropertiesTable from "./PropertiesTable.svelte";
   import ToggleLayer from "./ToggleLayer.svelte";
 
+  onMount(async () => {
+    await init();
+  });
+
   let colors = {
     origins: "blue",
     destinations: "purple",
diff --git a/viewer/src/PropertiesTable.svelte b/viewer/src/PropertiesTable.svelte
index ba4375f..8691c91 100644
--- a/viewer/src/PropertiesTable.svelte
+++ b/viewer/src/PropertiesTable.svelte
@@ -1,14 +1,26 @@
 <script lang="ts">
-  import { evaluateLTS } from "./lts";
+  import { calculate } from "lts";
 
   export let properties: { [name: string]: any };
 
-  let result = evaluateLTS({ tags: properties });
+  let tags = structuredClone(properties);
+  // TODO Organize the GJ output better in the first-place, nest OSM tags elsewhere
+  delete tags.count;
+  delete tags.lts;
+  delete tags.node1;
+  delete tags.node2;
+  delete tags.way;
+
+  let ltsResult = calculate({
+    method: "bike_ottawa",
+    tags,
+  });
 </script>
 
 <b>Count: {properties.count.toFixed(2)}</b>
+<b>LTS (Rust): {ltsResult.lts}</b>
 <ul>
-  {#each result.message as msg}
+  {#each ltsResult.messages as msg}
     <li>{msg}</li>
   {/each}
 </ul>
diff --git a/viewer/vite.config.ts b/viewer/vite.config.ts
index 60aa04b..bbeffb4 100644
--- a/viewer/vite.config.ts
+++ b/viewer/vite.config.ts
@@ -1,6 +1,7 @@
 import { defineConfig } from "vite";
 import { resolve } from "path";
 import { svelte } from "@sveltejs/vite-plugin-svelte";
+import wasmPack from "vite-plugin-wasm-pack";
 
 export default defineConfig({
   base: "/routing-engines/",
@@ -11,11 +12,5 @@ export default defineConfig({
       },
     },
   },
-  plugins: [svelte()],
-  // TODO For the symlinks in assets
-  server: {
-    fs: {
-      allow: [".."],
-    },
-  },
+  plugins: [svelte(), wasmPack(["../lts"], [])]
 })