diff --git a/.eslintrc.js b/.eslintrc.js
index f17a771cf870..137615d4a4f4 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -46,7 +46,7 @@ module.exports = {
     // Ignore certain webpack alias because it can't be resolved
     'import/no-unresolved': [
       ERROR,
-      {ignore: ['^@theme', '^@docusaurus', '^@generated']},
+      {ignore: ['^@theme', '^@docusaurus', '^@generated', 'unist', 'mdast']},
     ],
     'import/extensions': OFF,
     'header/header': [
diff --git a/packages/docusaurus-mdx-loader/package.json b/packages/docusaurus-mdx-loader/package.json
index 9296cf7f22d6..51150165ca36 100644
--- a/packages/docusaurus-mdx-loader/package.json
+++ b/packages/docusaurus-mdx-loader/package.json
@@ -2,8 +2,8 @@
   "name": "@docusaurus/mdx-loader",
   "version": "2.0.0-beta.4",
   "description": "Docusaurus Loader for MDX",
-  "main": "src/index.js",
-  "types": "src/index.d.ts",
+  "main": "lib/index.js",
+  "types": "src/types.d.ts",
   "publishConfig": {
     "access": "public"
   },
@@ -39,6 +39,10 @@
   },
   "devDependencies": {
     "@docusaurus/types": "2.0.0-beta.4",
+    "@types/escape-html": "^1.0.1",
+    "@types/mdast": "^3.0.7",
+    "@types/stringify-object": "^3.3.1",
+    "@types/unist": "^2.0.6",
     "remark": "^12.0.0",
     "remark-mdx": "^1.6.21",
     "to-vfile": "^6.0.0",
diff --git a/packages/docusaurus-mdx-loader/src/index.d.ts b/packages/docusaurus-mdx-loader/src/index.d.ts
deleted file mode 100644
index 0d13b2f37c79..000000000000
--- a/packages/docusaurus-mdx-loader/src/index.d.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-/**
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-type RemarkOrRehypePlugin =
-  // eslint-disable-next-line @typescript-eslint/ban-types
-  [Function, Record<string, unknown>] | Function;
-
-declare function docusaurusMdxLoader(fileString: string): string;
-
-export interface RemarkAndRehypePluginOptions {
-  remarkPlugins: RemarkOrRehypePlugin[];
-  rehypePlugins: string[];
-  beforeDefaultRemarkPlugins: RemarkOrRehypePlugin[];
-  beforeDefaultRehypePlugins: RemarkOrRehypePlugin[];
-}
diff --git a/packages/docusaurus-mdx-loader/src/index.js b/packages/docusaurus-mdx-loader/src/index.ts
similarity index 71%
rename from packages/docusaurus-mdx-loader/src/index.js
rename to packages/docusaurus-mdx-loader/src/index.ts
index bc555c1be525..cd02f412620b 100644
--- a/packages/docusaurus-mdx-loader/src/index.js
+++ b/packages/docusaurus-mdx-loader/src/index.ts
@@ -5,36 +5,45 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const {readFile} = require('fs-extra');
-const mdx = require('@mdx-js/mdx');
-const chalk = require('chalk');
-const emoji = require('remark-emoji');
-const {
+import {readFile} from 'fs-extra';
+import mdx from '@mdx-js/mdx';
+import chalk from 'chalk';
+import emoji from 'remark-emoji';
+import {
   parseFrontMatter,
   parseMarkdownContentTitle,
-} = require('@docusaurus/utils');
-const stringifyObject = require('stringify-object');
-const headings = require('./remark/headings');
-const toc = require('./remark/toc');
-const unwrapMdxCodeBlocks = require('./remark/unwrapMdxCodeBlocks');
-const transformImage = require('./remark/transformImage');
-const transformLinks = require('./remark/transformLinks');
-const {escapePath} = require('@docusaurus/utils');
-const {getFileLoaderUtils} = require('@docusaurus/core/lib/webpack/utils');
+  escapePath,
+} from '@docusaurus/utils';
+import stringifyObject from 'stringify-object';
+import headings from './remark/headings';
+import toc from './remark/toc';
+import unwrapMdxCodeBlocks from './remark/unwrapMdxCodeBlocks';
+import transformImage from './remark/transformImage';
+import transformLinks from './remark/transformLinks';
+import {getFileLoaderUtils} from '@docusaurus/core/lib/webpack/utils';
+import type {RemarkAndRehypePluginOptions} from '@docusaurus/mdx-loader';
+
+// TODO temporary until Webpack5 export this type
+// see https://github.com/webpack/webpack/issues/11630
+interface Loader extends Function {
+  (this: any, source: string): Promise<string | Buffer | void | undefined>;
+}
 
 const {
   loaders: {inlineMarkdownImageFileLoader},
 } = getFileLoaderUtils();
 
-const DEFAULT_OPTIONS = {
+const DEFAULT_OPTIONS: RemarkAndRehypePluginOptions = {
   rehypePlugins: [],
   remarkPlugins: [unwrapMdxCodeBlocks, emoji, headings, toc],
+  beforeDefaultRemarkPlugins: [],
+  beforeDefaultRehypePlugins: [],
 };
 
 // When this throws, it generally means that there's no metadata file associated with this MDX document
 // It can happen when using MDX partials (usually starting with _)
 // That's why it's important to provide the "isMDXPartial" function in config
-async function readMetadataPath(metadataPath) {
+async function readMetadataPath(metadataPath: string) {
   try {
     return await readFile(metadataPath, 'utf8');
   } catch (e) {
@@ -48,15 +57,14 @@ async function readMetadataPath(metadataPath) {
 // We don't do that for all frontMatters, only for the configured keys
 // {image: "./myImage.png"} => {image: require("./myImage.png")}
 function createFrontMatterAssetsExportCode(
-  filePath,
-  frontMatter,
-  frontMatterAssetKeys = [],
+  frontMatter: Record<string, unknown>,
+  frontMatterAssetKeys: string[] = [],
 ) {
   if (frontMatterAssetKeys.length === 0) {
     return 'undefined';
   }
 
-  function createFrontMatterAssetRequireCode(value) {
+  function createFrontMatterAssetRequireCode(value: unknown) {
     // Only process string values starting with ./
     // We could enhance this logic and check if file exists on disc?
     if (typeof value === 'string' && value.startsWith('./')) {
@@ -84,7 +92,7 @@ function createFrontMatterAssetsExportCode(
   return exportValue;
 }
 
-module.exports = async function docusaurusMdxLoader(fileString) {
+const docusaurusMdxLoader: Loader = async function (fileString) {
   const callback = this.async();
   const filePath = this.resourcePath;
   const reqOptions = this.getOptions() || {};
@@ -122,35 +130,25 @@ module.exports = async function docusaurusMdxLoader(fileString) {
     return callback(err);
   }
 
-  let exportStr = ``;
-  exportStr += `\nexport const frontMatter = ${stringifyObject(frontMatter)};`;
-  exportStr += `\nexport const frontMatterAssets = ${createFrontMatterAssetsExportCode(
-    filePath,
+  let exportStr = `
+export const frontMatter = ${stringifyObject(frontMatter)};
+export const frontMatterAssets = ${createFrontMatterAssetsExportCode(
     frontMatter,
     reqOptions.frontMatterAssetKeys,
-  )};`;
-  exportStr += `\nexport const contentTitle = ${stringifyObject(
-    contentTitle,
-  )};`;
+  )};
+export const contentTitle = ${stringifyObject(contentTitle)};`;
 
   // MDX partials are MDX files starting with _ or in a folder starting with _
   // Partial are not expected to have an associated metadata file or frontmatter
-  const isMDXPartial = options.isMDXPartial
-    ? options.isMDXPartial(filePath)
-    : false;
+  const isMDXPartial = options.isMDXPartial && options.isMDXPartial(filePath);
 
   if (isMDXPartial && hasFrontMatter) {
     const errorMessage = `Docusaurus MDX partial files should not contain FrontMatter.
 Those partial files use the _ prefix as a convention by default, but this is configurable.
-File at ${filePath} contains FrontMatter that will be ignored: \n${JSON.stringify(
-      frontMatter,
-      null,
-      2,
-    )}`;
-
-    if (options.isMDXPartialFrontMatterWarningDisabled === true) {
-      // no warning
-    } else {
+File at ${filePath} contains FrontMatter that will be ignored:
+${JSON.stringify(frontMatter, null, 2)}`;
+
+    if (!options.isMDXPartialFrontMatterWarningDisabled) {
       const shouldError = process.env.NODE_ENV === 'test' || process.env.CI;
       if (shouldError) {
         return callback(new Error(errorMessage));
@@ -176,12 +174,14 @@ File at ${filePath} contains FrontMatter that will be ignored: \n${JSON.stringif
   }
 
   const code = `
-  import React from 'react';
-  import { mdx } from '@mdx-js/react';
+import React from 'react';
+import { mdx } from '@mdx-js/react';
 
-  ${exportStr}
-  ${result}
-  `;
+${exportStr}
+${result}
+`;
 
   return callback(null, code);
 };
+
+export default docusaurusMdxLoader;
diff --git a/packages/docusaurus-mdx-loader/src/remark/headings/__tests__/index.test.js b/packages/docusaurus-mdx-loader/src/remark/headings/__tests__/index.test.ts
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/headings/__tests__/index.test.js
rename to packages/docusaurus-mdx-loader/src/remark/headings/__tests__/index.test.ts
diff --git a/packages/docusaurus-mdx-loader/src/remark/headings/index.js b/packages/docusaurus-mdx-loader/src/remark/headings/index.ts
similarity index 67%
rename from packages/docusaurus-mdx-loader/src/remark/headings/index.js
rename to packages/docusaurus-mdx-loader/src/remark/headings/index.ts
index 15e713a90707..957ecdd727c1 100644
--- a/packages/docusaurus-mdx-loader/src/remark/headings/index.js
+++ b/packages/docusaurus-mdx-loader/src/remark/headings/index.ts
@@ -7,18 +7,25 @@
 
 /* Based on remark-slug (https://github.com/remarkjs/remark-slug) and gatsby-remark-autolink-headers (https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-remark-autolink-headers) */
 
-const {parseMarkdownHeadingId} = require('@docusaurus/utils');
-const visit = require('unist-util-visit');
-const toString = require('mdast-util-to-string');
-const slugs = require('github-slugger')();
+import {parseMarkdownHeadingId} from '@docusaurus/utils';
+import visit, {Visitor} from 'unist-util-visit';
+import toString from 'mdast-util-to-string';
+import Slugger from 'github-slugger';
+import type {Transformer} from 'unified';
+import type {Parent} from 'unist';
+import type {Heading, Text} from 'mdast';
 
-function headings() {
-  const transformer = (ast) => {
+const slugs = new Slugger();
+
+function headings(): Transformer {
+  const transformer: Transformer = (ast) => {
     slugs.reset();
 
-    function visitor(headingNode) {
-      const data = headingNode.data || (headingNode.data = {}); // eslint-disable-line
-      const properties = data.hProperties || (data.hProperties = {});
+    const visitor: Visitor<Heading> = (headingNode) => {
+      const data = headingNode.data || (headingNode.data = {});
+      const properties = (data.hProperties || (data.hProperties = {})) as {
+        id: string;
+      };
       let {id} = properties;
 
       if (id) {
@@ -29,7 +36,7 @@ function headings() {
         );
         const heading = toString(
           headingTextNodes.length > 0
-            ? {children: headingTextNodes}
+            ? ({children: headingTextNodes} as Parent)
             : headingNode,
         );
 
@@ -42,8 +49,9 @@ function headings() {
           // When there's an id, it is always in the last child node
           // Sometimes heading is in multiple "parts" (** syntax creates a child node):
           // ## part1 *part2* part3 {#id}
-          const lastNode =
-            headingNode.children[headingNode.children.length - 1];
+          const lastNode = headingNode.children[
+            headingNode.children.length - 1
+          ] as Text;
 
           if (headingNode.children.length > 1) {
             const lastNodeText = parseMarkdownHeadingId(lastNode.value).text;
@@ -63,7 +71,7 @@ function headings() {
 
       data.id = id;
       properties.id = id;
-    }
+    };
 
     visit(ast, 'heading', visitor);
   };
@@ -71,4 +79,4 @@ function headings() {
   return transformer;
 }
 
-module.exports = headings;
+export default headings;
diff --git a/packages/docusaurus-mdx-loader/src/remark/toc/__tests__/__snapshots__/index.test.js.snap b/packages/docusaurus-mdx-loader/src/remark/toc/__tests__/__snapshots__/index.test.ts.snap
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/toc/__tests__/__snapshots__/index.test.js.snap
rename to packages/docusaurus-mdx-loader/src/remark/toc/__tests__/__snapshots__/index.test.ts.snap
diff --git a/packages/docusaurus-mdx-loader/src/remark/toc/__tests__/index.test.js b/packages/docusaurus-mdx-loader/src/remark/toc/__tests__/index.test.ts
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/toc/__tests__/index.test.js
rename to packages/docusaurus-mdx-loader/src/remark/toc/__tests__/index.test.ts
diff --git a/packages/docusaurus-mdx-loader/src/remark/toc/index.js b/packages/docusaurus-mdx-loader/src/remark/toc/index.ts
similarity index 56%
rename from packages/docusaurus-mdx-loader/src/remark/toc/index.js
rename to packages/docusaurus-mdx-loader/src/remark/toc/index.ts
index 949a7467bcab..7985cae903f2 100644
--- a/packages/docusaurus-mdx-loader/src/remark/toc/index.js
+++ b/packages/docusaurus-mdx-loader/src/remark/toc/index.ts
@@ -5,34 +5,42 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const {parse} = require('@babel/parser');
-const traverse = require('@babel/traverse').default;
-const stringifyObject = require('stringify-object');
-const search = require('./search');
+import {parse, ParserOptions} from '@babel/parser';
+import type {Identifier} from '@babel/types';
+import traverse from '@babel/traverse';
+import stringifyObject from 'stringify-object';
+import search from './search';
+import type {Plugin, Transformer} from 'unified';
+import type {Node, Parent} from 'unist';
+import type {Literal} from 'mdast';
 
-const parseOptions = {
+const parseOptions: ParserOptions = {
   plugins: ['jsx'],
   sourceType: 'module',
 };
-const isImport = (child) => child.type === 'import';
-const hasImports = (index) => index > -1;
-const isExport = (child) => child.type === 'export';
 
-const isTarget = (child, name) => {
+const isImport = (child: Node): child is Literal => child.type === 'import';
+const hasImports = (index: number) => index > -1;
+const isExport = (child: Node): child is Literal => child.type === 'export';
+
+interface PluginOptions {
+  name?: string;
+}
+
+const isTarget = (child: Literal, name: string) => {
   let found = false;
   const ast = parse(child.value, parseOptions);
   traverse(ast, {
     VariableDeclarator: (path) => {
-      if (path.node.id.name === name) {
+      if ((path.node.id as Identifier).name === name) {
         found = true;
       }
     },
   });
-
   return found;
 };
 
-const getOrCreateExistingTargetIndex = (children, name) => {
+const getOrCreateExistingTargetIndex = (children: Node[], name: string) => {
   let importsIndex = -1;
   let targetIndex = -1;
 
@@ -58,12 +66,12 @@ const getOrCreateExistingTargetIndex = (children, name) => {
   return targetIndex;
 };
 
-const plugin = (options = {}) => {
+const plugin: Plugin<[PluginOptions?]> = (options = {}) => {
   const name = options.name || 'toc';
 
-  const transformer = (node) => {
+  const transformer: Transformer = (node) => {
     const headings = search(node);
-    const {children} = node;
+    const {children} = node as Parent<Literal>;
     const targetIndex = getOrCreateExistingTargetIndex(children, name);
 
     if (headings && headings.length) {
@@ -76,4 +84,4 @@ const plugin = (options = {}) => {
   return transformer;
 };
 
-module.exports = plugin;
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/toc/search.js b/packages/docusaurus-mdx-loader/src/remark/toc/search.js
deleted file mode 100644
index 3d8b869d390a..000000000000
--- a/packages/docusaurus-mdx-loader/src/remark/toc/search.js
+++ /dev/null
@@ -1,73 +0,0 @@
-/**
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-// @ts-check
-
-const toString = require('mdast-util-to-string');
-const visit = require('unist-util-visit');
-// Destructuring require tslib
-// eslint-disable-next-line prefer-destructuring
-const toValue = require('../utils').toValue;
-
-/** @typedef {import('@docusaurus/types').TOCItem} TOC */
-/** @typedef {import('unist').Node} Node */
-
-/**
- * @typedef {Object} StringValuedNode
- * @property {string} type
- * @property {string} value
- * @property {number} depth
- * @property {Object} data
- * @property {StringValuedNode[]} children
- */
-
-// Visit all headings. We `slug` all headings (to account for
-// duplicates), but only take h2 and h3 headings.
-/**
- * @param {StringValuedNode} node
- * @returns {TOC[]}
- */
-function search(node) {
-  /** @type {TOC[]} */
-  const headings = [];
-  let current = -1;
-  let currentDepth = 0;
-
-  /**
-   * @param {StringValuedNode} child
-   * @param {number} index
-   * @param {Node | undefined} parent
-   * @returns {void}
-   */
-  const onHeading = (child, index, parent) => {
-    const value = toString(child);
-
-    if (parent !== node || !value || child.depth > 3 || child.depth < 2) {
-      return;
-    }
-
-    const entry = {
-      value: toValue(child),
-      id: child.data.id,
-      children: [],
-    };
-
-    if (!headings.length || currentDepth >= child.depth) {
-      headings.push(entry);
-      current += 1;
-      currentDepth = child.depth;
-    } else {
-      headings[current].children.push(entry);
-    }
-  };
-
-  visit(node, 'heading', onHeading);
-
-  return headings;
-}
-
-module.exports = search;
diff --git a/packages/docusaurus-mdx-loader/src/remark/toc/search.ts b/packages/docusaurus-mdx-loader/src/remark/toc/search.ts
new file mode 100644
index 000000000000..112a56c3fab2
--- /dev/null
+++ b/packages/docusaurus-mdx-loader/src/remark/toc/search.ts
@@ -0,0 +1,47 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import toString from 'mdast-util-to-string';
+import visit, {Visitor} from 'unist-util-visit';
+import {toValue} from '../utils';
+import type {TOCItem as TOC} from '@docusaurus/types';
+import type {Node} from 'unist';
+import type {Heading} from 'mdast';
+
+// Visit all headings. We `slug` all headings (to account for
+// duplicates), but only take h2 and h3 headings.
+export default function search(node: Node): TOC[] {
+  const headings: TOC[] = [];
+  let current = -1;
+  let currentDepth = 0;
+
+  const visitor: Visitor<Heading> = (child, _index, parent) => {
+    const value = toString(child);
+
+    if (parent !== node || !value || child.depth > 3 || child.depth < 2) {
+      return;
+    }
+
+    const entry: TOC = {
+      value: toValue(child),
+      id: child.data!.id as string,
+      children: [],
+    };
+
+    if (!headings.length || currentDepth >= child.depth) {
+      headings.push(entry);
+      current += 1;
+      currentDepth = child.depth;
+    } else {
+      headings[current].children.push(entry);
+    }
+  };
+
+  visit(node, 'heading', visitor);
+
+  return headings;
+}
diff --git a/packages/docusaurus-mdx-loader/src/remark/transformImage/__tests__/__snapshots__/index.test.js.snap b/packages/docusaurus-mdx-loader/src/remark/transformImage/__tests__/__snapshots__/index.test.ts.snap
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/transformImage/__tests__/__snapshots__/index.test.js.snap
rename to packages/docusaurus-mdx-loader/src/remark/transformImage/__tests__/__snapshots__/index.test.ts.snap
diff --git a/packages/docusaurus-mdx-loader/src/remark/transformImage/__tests__/index.test.js b/packages/docusaurus-mdx-loader/src/remark/transformImage/__tests__/index.test.ts
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/transformImage/__tests__/index.test.js
rename to packages/docusaurus-mdx-loader/src/remark/transformImage/__tests__/index.test.ts
diff --git a/packages/docusaurus-mdx-loader/src/remark/transformImage/index.js b/packages/docusaurus-mdx-loader/src/remark/transformImage/index.ts
similarity index 69%
rename from packages/docusaurus-mdx-loader/src/remark/transformImage/index.js
rename to packages/docusaurus-mdx-loader/src/remark/transformImage/index.ts
index 4afcc5136e1c..2e77a52d864d 100644
--- a/packages/docusaurus-mdx-loader/src/remark/transformImage/index.js
+++ b/packages/docusaurus-mdx-loader/src/remark/transformImage/index.ts
@@ -5,26 +5,35 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const visit = require('unist-util-visit');
-const path = require('path');
-const url = require('url');
-const fs = require('fs-extra');
-const escapeHtml = require('escape-html');
-const {getFileLoaderUtils} = require('@docusaurus/core/lib/webpack/utils');
-const {
+import visit from 'unist-util-visit';
+import path from 'path';
+import url from 'url';
+import fs from 'fs-extra';
+import escapeHtml from 'escape-html';
+import {getFileLoaderUtils} from '@docusaurus/core/lib/webpack/utils';
+import {
   posixPath,
   escapePath,
   toMessageRelativeFilePath,
-} = require('@docusaurus/utils');
+} from '@docusaurus/utils';
+import type {Plugin, Transformer} from 'unified';
+import type {Image, Literal} from 'mdast';
 
 const {
   loaders: {inlineMarkdownImageFileLoader},
 } = getFileLoaderUtils();
 
-const createJSX = (node, pathUrl) => {
+interface PluginOptions {
+  filePath: string;
+  staticDir: string;
+}
+
+const createJSX = (node: Image, pathUrl: string) => {
   const jsxNode = node;
-  jsxNode.type = 'jsx';
-  jsxNode.value = `<img ${node.alt ? `alt={"${escapeHtml(node.alt)}"} ` : ''}${
+  ((jsxNode as unknown) as Literal).type = 'jsx';
+  ((jsxNode as unknown) as Literal).value = `<img ${
+    node.alt ? `alt={"${escapeHtml(node.alt)}"} ` : ''
+  }${
     node.url
       ? `src={require("${inlineMarkdownImageFileLoader}${escapePath(
           pathUrl,
@@ -33,7 +42,7 @@ const createJSX = (node, pathUrl) => {
   }${node.title ? ` title="${escapeHtml(node.title)}"` : ''} />`;
 
   if (jsxNode.url) {
-    delete jsxNode.url;
+    delete (jsxNode as Partial<Image>).url;
   }
   if (jsxNode.alt) {
     delete jsxNode.alt;
@@ -43,7 +52,7 @@ const createJSX = (node, pathUrl) => {
   }
 };
 
-async function ensureImageFileExist(imagePath, sourceFilePath) {
+async function ensureImageFileExist(imagePath: string, sourceFilePath: string) {
   const imageExists = await fs.pathExists(imagePath);
   if (!imageExists) {
     throw new Error(
@@ -54,7 +63,10 @@ async function ensureImageFileExist(imagePath, sourceFilePath) {
   }
 }
 
-async function processImageNode(node, {filePath, staticDir}) {
+async function processImageNode(
+  node: Image,
+  {filePath, staticDir}: PluginOptions,
+) {
   if (!node.url) {
     throw new Error(
       `Markdown image URL is mandatory in "${toMessageRelativeFilePath(
@@ -71,8 +83,6 @@ async function processImageNode(node, {filePath, staticDir}) {
     // it's mostly to make next release less risky (2.0.0-alpha.59)
     if (parsedUrl.protocol === 'pathname:') {
       node.url = node.url.replace('pathname://', '');
-    } else {
-      // noop
     }
   }
   // images without protocol
@@ -92,10 +102,10 @@ async function processImageNode(node, {filePath, staticDir}) {
   }
 }
 
-const plugin = (options) => {
-  const transformer = async (root) => {
-    const promises = [];
-    visit(root, 'image', (node) => {
+const plugin: Plugin<[PluginOptions]> = (options) => {
+  const transformer: Transformer = async (root) => {
+    const promises: Promise<void>[] = [];
+    visit(root, 'image', (node: Image) => {
       promises.push(processImageNode(node, options));
     });
     await Promise.all(promises);
@@ -103,4 +113,4 @@ const plugin = (options) => {
   return transformer;
 };
 
-module.exports = plugin;
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/transformLinks/__tests__/__snapshots__/index.test.js.snap b/packages/docusaurus-mdx-loader/src/remark/transformLinks/__tests__/__snapshots__/index.test.ts.snap
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/transformLinks/__tests__/__snapshots__/index.test.js.snap
rename to packages/docusaurus-mdx-loader/src/remark/transformLinks/__tests__/__snapshots__/index.test.ts.snap
diff --git a/packages/docusaurus-mdx-loader/src/remark/transformLinks/__tests__/index.test.js b/packages/docusaurus-mdx-loader/src/remark/transformLinks/__tests__/index.test.ts
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/transformLinks/__tests__/index.test.js
rename to packages/docusaurus-mdx-loader/src/remark/transformLinks/__tests__/index.test.ts
diff --git a/packages/docusaurus-mdx-loader/src/remark/transformLinks/index.js b/packages/docusaurus-mdx-loader/src/remark/transformLinks/index.ts
similarity index 64%
rename from packages/docusaurus-mdx-loader/src/remark/transformLinks/index.js
rename to packages/docusaurus-mdx-loader/src/remark/transformLinks/index.ts
index 4ca56997eb53..e17aad681a67 100644
--- a/packages/docusaurus-mdx-loader/src/remark/transformLinks/index.js
+++ b/packages/docusaurus-mdx-loader/src/remark/transformLinks/index.ts
@@ -5,25 +5,34 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const {
+import {
   toMessageRelativeFilePath,
   posixPath,
   escapePath,
-} = require('@docusaurus/utils');
-
-const visit = require('unist-util-visit');
-const path = require('path');
-const url = require('url');
-const fs = require('fs-extra');
-const escapeHtml = require('escape-html');
-const {toValue} = require('../utils');
-const {getFileLoaderUtils} = require('@docusaurus/core/lib/webpack/utils');
+} from '@docusaurus/utils';
+import visit from 'unist-util-visit';
+import path from 'path';
+import url from 'url';
+import fs from 'fs-extra';
+import escapeHtml from 'escape-html';
+import {stringifyContent} from '../utils';
+import {getFileLoaderUtils} from '@docusaurus/core/lib/webpack/utils';
+import type {Plugin, Transformer} from 'unified';
+import type {Link, Literal} from 'mdast';
 
 const {
   loaders: {inlineMarkdownLinkFileLoader},
 } = getFileLoaderUtils();
 
-async function ensureAssetFileExist(fileSystemAssetPath, sourceFilePath) {
+interface PluginOptions {
+  filePath: string;
+  staticDir: string;
+}
+
+async function ensureAssetFileExist(
+  fileSystemAssetPath: string,
+  sourceFilePath: string,
+) {
   const assetExists = await fs.pathExists(fileSystemAssetPath);
   if (!assetExists) {
     throw new Error(
@@ -35,7 +44,15 @@ async function ensureAssetFileExist(fileSystemAssetPath, sourceFilePath) {
 }
 
 // transform the link node to a jsx link with a require() call
-function toAssetRequireNode({node, filePath, requireAssetPath}) {
+function toAssetRequireNode({
+  node,
+  filePath,
+  requireAssetPath,
+}: {
+  node: Link;
+  filePath: string;
+  requireAssetPath: string;
+}) {
   /* eslint-disable no-param-reassign */
 
   let relativeRequireAssetPath = posixPath(
@@ -50,17 +67,21 @@ function toAssetRequireNode({node, filePath, requireAssetPath}) {
   const href = `require('${inlineMarkdownLinkFileLoader}${escapePath(
     relativeRequireAssetPath,
   )}').default`;
-  const children = (node.children || []).map((n) => toValue(n)).join('');
+  const children = stringifyContent(node);
   const title = node.title ? `title="${escapeHtml(node.title)}"` : '';
 
-  node.type = 'jsx';
-  node.value = `<a target="_blank" href={${href}}${title}>${children}</a>`;
+  ((node as unknown) as Literal).type = 'jsx';
+  ((node as unknown) as Literal).value = `<a target="_blank" href={${href}}${title}>${children}</a>`;
 }
 
 // If the link looks like an asset link, we'll link to the asset,
 // and use a require("assetUrl") (using webpack url-loader/file-loader)
 // instead of navigating to such link
-async function convertToAssetLinkIfNeeded({node, staticDir, filePath}) {
+async function convertToAssetLinkIfNeeded({
+  node,
+  staticDir,
+  filePath,
+}: {node: Link} & PluginOptions) {
   const assetPath = node.url;
 
   const hasSiteAlias = assetPath.startsWith('@site/');
@@ -73,7 +94,7 @@ async function convertToAssetLinkIfNeeded({node, staticDir, filePath}) {
     return;
   }
 
-  function toAssetLinkNode(requireAssetPath) {
+  function toAssetLinkNode(requireAssetPath: string) {
     toAssetRequireNode({
       node,
       filePath,
@@ -102,14 +123,16 @@ async function convertToAssetLinkIfNeeded({node, staticDir, filePath}) {
   }
 }
 
-async function processLinkNode({node, _index, _parent, filePath, staticDir}) {
+async function processLinkNode({
+  node,
+  filePath,
+  staticDir,
+}: {node: Link} & PluginOptions) {
   if (!node.url) {
     // try to improve error feedback
     // see https://github.com/facebook/docusaurus/issues/3309#issuecomment-690371675
-    const title =
-      node.title || (node.children[0] && node.children[0].value) || '?';
-    const line =
-      (node.position && node.position.start && node.position.start.line) || '?';
+    const title = node.title || (node.children[0] as Literal)?.value || '?';
+    const line = node?.position?.start?.line || '?';
     throw new Error(
       `Markdown link URL is mandatory in "${toMessageRelativeFilePath(
         filePath,
@@ -122,22 +145,18 @@ async function processLinkNode({node, _index, _parent, filePath, staticDir}) {
     return;
   }
 
-  await convertToAssetLinkIfNeeded({
-    node,
-    staticDir,
-    filePath,
-  });
+  await convertToAssetLinkIfNeeded({node, staticDir, filePath});
 }
 
-const plugin = (options) => {
-  const transformer = async (root) => {
-    const promises = [];
-    visit(root, 'link', (node, index, parent) => {
-      promises.push(processLinkNode({node, index, parent, ...options}));
+const plugin: Plugin<[PluginOptions]> = (options) => {
+  const transformer: Transformer = async (root) => {
+    const promises: Promise<void>[] = [];
+    visit(root, 'link', (node: Link) => {
+      promises.push(processLinkNode({node, ...options}));
     });
     await Promise.all(promises);
   };
   return transformer;
 };
 
-module.exports = plugin;
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/__tests__/__snapshots__/index.test.js.snap b/packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/__tests__/__snapshots__/index.test.ts.snap
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/__tests__/__snapshots__/index.test.js.snap
rename to packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/__tests__/__snapshots__/index.test.ts.snap
diff --git a/packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/__tests__/index.test.js b/packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/__tests__/index.test.ts
similarity index 100%
rename from packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/__tests__/index.test.js
rename to packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/__tests__/index.test.ts
diff --git a/packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/index.js b/packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/index.ts
similarity index 60%
rename from packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/index.js
rename to packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/index.ts
index 23d957312e9e..101f2552e6b9 100644
--- a/packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/index.js
+++ b/packages/docusaurus-mdx-loader/src/remark/unwrapMdxCodeBlocks/index.ts
@@ -5,24 +5,26 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const visit = require('unist-util-visit');
+import visit from 'unist-util-visit';
+import type {Transformer, Processor} from 'unified';
+import type {Code, Parent} from 'mdast';
 
 // This plugin is mostly to help integrating Docusaurus with translation systems
 // that do not support well MDX embedded JSX syntax (like Crowdin)
 // We wrap the JSX syntax in code blocks so that translation tools don't mess-up with the markup
 // But the JSX inside such code blocks should still be evaluated as JSX
 // See https://github.com/facebook/docusaurus/pull/4278
-function plugin() {
-  const transformer = (root) => {
-    visit(root, 'code', (node, _index, parent) => {
+function plugin(this: Processor): Transformer {
+  const transformer: Transformer = (root) => {
+    visit(root, 'code', (node: Code, _index, parent) => {
       if (node.lang === 'mdx-code-block') {
-        const newChildrens = this.parse(node.value).children;
+        const newChildren = (this!.parse(node.value) as Parent).children;
 
         // Replace the mdx code block by its content, parsed
-        parent.children.splice(
-          parent.children.indexOf(node),
+        parent!.children.splice(
+          parent!.children.indexOf(node),
           1,
-          ...newChildrens,
+          ...newChildren,
         );
       }
     });
@@ -31,4 +33,4 @@ function plugin() {
   return transformer;
 }
 
-module.exports = plugin;
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/utils/index.js b/packages/docusaurus-mdx-loader/src/remark/utils/index.js
deleted file mode 100644
index 0cdf55733bc5..000000000000
--- a/packages/docusaurus-mdx-loader/src/remark/utils/index.js
+++ /dev/null
@@ -1,39 +0,0 @@
-/**
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-const escapeHtml = require('escape-html');
-const toString = require('mdast-util-to-string');
-
-/**
- * @param {StringValuedNode | undefined} node
- * @returns {string}
- */
-function toValue(node) {
-  if (node && node.type) {
-    switch (node.type) {
-      case 'text':
-        return escapeHtml(node.value);
-      case 'heading':
-        return node.children.map(toValue).join('');
-      case 'inlineCode':
-        return `<code>${escapeHtml(node.value)}</code>`;
-      case 'emphasis':
-        return `<em>${node.children.map(toValue).join('')}</em>`;
-      case 'strong':
-        return `<strong>${node.children.map(toValue).join('')}</strong>`;
-      case 'delete':
-        return `<del>${node.children.map(toValue).join('')}</del>`;
-      default:
-    }
-  }
-
-  return toString(node);
-}
-
-module.exports = {
-  toValue,
-};
diff --git a/packages/docusaurus-mdx-loader/src/remark/utils/index.ts b/packages/docusaurus-mdx-loader/src/remark/utils/index.ts
new file mode 100644
index 000000000000..2309a8dd10ea
--- /dev/null
+++ b/packages/docusaurus-mdx-loader/src/remark/utils/index.ts
@@ -0,0 +1,39 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import escapeHtml from 'escape-html';
+import toString from 'mdast-util-to-string';
+import type {Parent} from 'unist';
+import type {StaticPhrasingContent, Heading} from 'mdast';
+
+export function stringifyContent(node: Parent): string {
+  return ((node.children || []) as StaticPhrasingContent[])
+    .map(toValue)
+    .join('');
+}
+
+export function toValue(node: StaticPhrasingContent | Heading): string {
+  if (node && node.type) {
+    switch (node.type) {
+      case 'text':
+        return escapeHtml(node.value);
+      case 'heading':
+        return stringifyContent(node);
+      case 'inlineCode':
+        return `<code>${escapeHtml(node.value)}</code>`;
+      case 'emphasis':
+        return `<em>${stringifyContent(node)}</em>`;
+      case 'strong':
+        return `<strong>${stringifyContent(node)}</strong>`;
+      case 'delete':
+        return `<del>${stringifyContent(node)}</del>`;
+      default:
+    }
+  }
+
+  return toString(node);
+}
diff --git a/packages/docusaurus-mdx-loader/src/types.d.ts b/packages/docusaurus-mdx-loader/src/types.d.ts
new file mode 100644
index 000000000000..8586ee373231
--- /dev/null
+++ b/packages/docusaurus-mdx-loader/src/types.d.ts
@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+declare module '@docusaurus/mdx-loader' {
+  export interface RemarkAndRehypePluginOptions {
+    remarkPlugins: RemarkOrRehypePlugin[];
+    rehypePlugins: string[];
+    beforeDefaultRemarkPlugins: RemarkOrRehypePlugin[];
+    beforeDefaultRehypePlugins: RemarkOrRehypePlugin[];
+  }
+}
+
+// TODO Types provided by MDX 2.0 https://github.com/mdx-js/mdx/blob/main/packages/mdx/types/index.d.ts
+declare module '@mdx-js/mdx' {
+  import type {Plugin, Processor} from 'unified';
+
+  export namespace mdx {
+    interface Options {
+      filepath?: string;
+      skipExport?: boolean;
+      wrapExport?: string;
+      remarkPlugins?: Plugin[];
+      rehypePlugins?: Plugin[];
+    }
+
+    function sync(content: string, options?: Options): string;
+    function createMdxAstCompiler(options?: Options): Processor;
+    function createCompiler(options?: Options): Processor;
+  }
+  export default function mdx(
+    content: string,
+    options?: mdx.Options,
+  ): Promise<string>;
+}
diff --git a/packages/docusaurus-mdx-loader/tsconfig.json b/packages/docusaurus-mdx-loader/tsconfig.json
index 460667f655b5..c85b6f78938c 100644
--- a/packages/docusaurus-mdx-loader/tsconfig.json
+++ b/packages/docusaurus-mdx-loader/tsconfig.json
@@ -1,9 +1,10 @@
 {
   "extends": "../../tsconfig.json",
   "compilerOptions": {
-    "allowJs": true,
-    "noEmit": true,
-    "noImplicitAny": false
+    "incremental": true,
+    "tsBuildInfoFile": "./lib/.tsbuildinfo",
+    "rootDir": "src",
+    "outDir": "lib"
   },
   "include": ["src/"]
 }
diff --git a/packages/docusaurus-migrate/src/sanitizeMD.ts b/packages/docusaurus-migrate/src/sanitizeMD.ts
index c182073ffbb5..1ebecb01c339 100644
--- a/packages/docusaurus-migrate/src/sanitizeMD.ts
+++ b/packages/docusaurus-migrate/src/sanitizeMD.ts
@@ -13,6 +13,7 @@ import visit from 'unist-util-visit';
 import remarkStringify from 'remark-stringify';
 import htmlTags from 'html-tags';
 import toText from 'hast-util-to-string';
+import type {Code, InlineCode} from 'mdast';
 
 const tags = htmlTags.reduce((acc: {[key: string]: boolean}, tag) => {
   acc[tag] = true;
@@ -21,10 +22,10 @@ const tags = htmlTags.reduce((acc: {[key: string]: boolean}, tag) => {
 
 export default function sanitizeMD(code: string): string {
   const markdownTree = unified().use(markdown).parse(code);
-  visit(markdownTree, 'code', (node) => {
+  visit(markdownTree, 'code', (node: Code) => {
     node.value = `\n<!--${node.value}-->\n`;
   });
-  visit(markdownTree, 'inlineCode', (node) => {
+  visit(markdownTree, 'inlineCode', (node: InlineCode) => {
     node.value = `<!--${node.value}-->`;
   });
 
@@ -33,7 +34,7 @@ export default function sanitizeMD(code: string): string {
     .stringify(markdownTree);
 
   const htmlTree = unified().use(parse).parse(markdownString);
-  visit(htmlTree, 'element', (node) => {
+  visit(htmlTree, 'element', (node: any) => {
     if (!tags[node.tagName as string]) {
       node.type = 'text';
       node.value = node.tagName + toText(node);
diff --git a/packages/docusaurus/src/server/html-tags/htmlTags.ts b/packages/docusaurus/src/server/html-tags/htmlTags.ts
index c27d64487ac4..a1d063d460de 100644
--- a/packages/docusaurus/src/server/html-tags/htmlTags.ts
+++ b/packages/docusaurus/src/server/html-tags/htmlTags.ts
@@ -42,7 +42,9 @@ export default function htmlTagObjectToString(tagDefinition: unknown): string {
       if (tagAttributes[attributeName] === true) {
         return attributeName;
       }
-      return `${attributeName}="${escapeHTML(tagAttributes[attributeName])}"`;
+      return `${attributeName}="${escapeHTML(
+        tagAttributes[attributeName] as string,
+      )}"`;
     });
   return `<${[tagDefinition.tagName].concat(attributes).join(' ')}>${
     (!isVoidTag && tagDefinition.innerHTML) || ''
diff --git a/yarn.lock b/yarn.lock
index 5ba4bfb5ec16..7375b28b210c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3994,6 +3994,11 @@
     "@types/got" "^8"
     "@types/node" "*"
 
+"@types/escape-html@^1.0.1":
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/@types/escape-html/-/escape-html-1.0.1.tgz#b19b4646915f0ae2c306bf984dc0a59c5cfc97ba"
+  integrity sha512-4mI1FuUUZiuT95fSVqvZxp/ssQK9zsa86S43h9x3zPOSU9BBJ+BfDkXwuaU7BfsD+e7U0/cUUfJFk3iW2M4okA==
+
 "@types/eslint-scope@^3.7.0":
   version "3.7.0"
   resolved "https://registry.yarnpkg.com/@types/eslint-scope/-/eslint-scope-3.7.0.tgz#4792816e31119ebd506902a482caec4951fabd86"
@@ -4208,10 +4213,10 @@
   resolved "https://registry.yarnpkg.com/@types/lodash/-/lodash-4.14.170.tgz#0d67711d4bf7f4ca5147e9091b847479b87925d6"
   integrity sha512-bpcvu/MKHHeYX+qeEN8GE7DIravODWdACVA1ctevD8CN24RhPZIKMn9ntfAsrvLfSX3cR5RrBKAbYm9bGs0A+Q==
 
-"@types/mdast@^3.0.0":
-  version "3.0.3"
-  resolved "https://registry.yarnpkg.com/@types/mdast/-/mdast-3.0.3.tgz#2d7d671b1cd1ea3deb306ea75036c2a0407d2deb"
-  integrity sha512-SXPBMnFVQg1s00dlMCc/jCdvPqdE4mXaMMCeRlxLDmTAEoegHT53xKtkDnzDTOcmMHUfcjyf36/YYZ6SxRdnsw==
+"@types/mdast@^3.0.0", "@types/mdast@^3.0.7":
+  version "3.0.7"
+  resolved "https://registry.yarnpkg.com/@types/mdast/-/mdast-3.0.7.tgz#cba63d0cc11eb1605cea5c0ad76e02684394166b"
+  integrity sha512-YwR7OK8aPmaBvMMUi+pZXBNoW2unbVbfok4YRqGMJBe1dpDlzpRkJrYEYmvjxgs5JhuQmKfDexrN98u941Zasg==
   dependencies:
     "@types/unist" "*"
 
@@ -4462,6 +4467,11 @@
   resolved "https://registry.yarnpkg.com/@types/stack-utils/-/stack-utils-2.0.0.tgz#7036640b4e21cc2f259ae826ce843d277dad8cff"
   integrity sha512-RJJrrySY7A8havqpGObOB4W92QXKJo63/jFLLgpvOtsGUqbQZ9Sbgl35KMm1DjC6j7AvmmU2bIno+3IyEaemaw==
 
+"@types/stringify-object@^3.3.1":
+  version "3.3.1"
+  resolved "https://registry.yarnpkg.com/@types/stringify-object/-/stringify-object-3.3.1.tgz#9ee394931e63468de0412a8e19c9f021a7d1d24d"
+  integrity sha512-bpCBW0O+QrMLNFBY/+rkZtGzcYRmc2aTD8qYHOMNUmednqETfEZtFcGEA11l9xqbIeiT1PgXG0eq3zqayVzZSQ==
+
 "@types/tapable@^1":
   version "1.0.7"
   resolved "https://registry.yarnpkg.com/@types/tapable/-/tapable-1.0.7.tgz#545158342f949e8fd3bfd813224971ecddc3fac4"
@@ -4474,10 +4484,10 @@
   dependencies:
     source-map "^0.6.1"
 
-"@types/unist@*", "@types/unist@^2.0.0", "@types/unist@^2.0.2", "@types/unist@^2.0.3":
-  version "2.0.3"
-  resolved "https://registry.yarnpkg.com/@types/unist/-/unist-2.0.3.tgz#9c088679876f374eb5983f150d4787aa6fb32d7e"
-  integrity sha512-FvUupuM3rlRsRtCN+fDudtmytGO6iHJuuRKS1Ss0pG5z8oX0diNEw94UEL7hgDbpN94rgaK5R7sWm6RrSkZuAQ==
+"@types/unist@*", "@types/unist@^2.0.0", "@types/unist@^2.0.2", "@types/unist@^2.0.3", "@types/unist@^2.0.6":
+  version "2.0.6"
+  resolved "https://registry.yarnpkg.com/@types/unist/-/unist-2.0.6.tgz#250a7b16c3b91f672a24552ec64678eeb1d3a08d"
+  integrity sha512-PBjIUxZHOuj0R15/xuwJYjFi+KZdNFrehocChv4g5hu6aFroHue8m0lBP0POdK2nKzbw0cgV1mws8+V/JAcEkQ==
 
 "@types/wait-on@^5.2.0":
   version "5.3.0"