diff --git a/.eslintignore b/.eslintignore
index 2854c10c59..b0c14dbeea 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -11,7 +11,6 @@ examples/
 packages/lqip-loader/lib/
 packages/docusaurus/lib/
 packages/docusaurus-*/lib/*
-packages/docusaurus-*/lib-next/
 packages/eslint-plugin/lib/
 packages/stylelint-copyright/lib/
 
diff --git a/.gitignore b/.gitignore
index 0e0bd14648..1e61285322 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,7 +25,6 @@ packages/docusaurus/lib/
 packages/docusaurus-*/lib/*
 packages/eslint-plugin/lib/
 packages/stylelint-copyright/lib/
-packages/docusaurus-*/lib-next/
 
 website/netlifyDeployPreview/*
 website/changelog
diff --git a/.prettierignore b/.prettierignore
index c7aec4e026..5bfdf4925c 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -7,7 +7,6 @@ coverage
 packages/lqip-loader/lib/
 packages/docusaurus/lib/
 packages/docusaurus-*/lib/*
-packages/docusaurus-*/lib-next/
 packages/create-docusaurus/lib/*
 packages/create-docusaurus/templates/*/docusaurus.config.js
 packages/eslint-plugin/lib/
diff --git a/.stylelintignore b/.stylelintignore
index 951af3a16e..15db7860ba 100644
--- a/.stylelintignore
+++ b/.stylelintignore
@@ -10,7 +10,6 @@ examples/
 packages/lqip-loader/lib/
 packages/docusaurus/lib/
 packages/docusaurus-*/lib/*
-packages/docusaurus-*/lib-next/
 packages/create-docusaurus/lib/*
 packages/create-docusaurus/templates/
 website/static/katex/katex.min.css
diff --git a/jest.config.mjs b/jest.config.mjs
index 28ba5e66a6..5e7200416b 100644
--- a/jest.config.mjs
+++ b/jest.config.mjs
@@ -23,7 +23,6 @@ const ignorePatterns = [
   '/packages/docusaurus-plugin-content-docs/lib',
   '/packages/docusaurus-plugin-content-pages/lib',
   '/packages/docusaurus-theme-classic/lib',
-  '/packages/docusaurus-theme-classic/lib-next',
   '/packages/docusaurus-theme-common/lib',
   '/packages/docusaurus-migrate/lib',
   '/jest',
diff --git a/package.json b/package.json
index eb257678d7..de33e023d0 100644
--- a/package.json
+++ b/package.json
@@ -54,7 +54,7 @@
     "test": "jest",
     "test:build:website": "./admin/scripts/test-release.sh",
     "watch": "yarn lerna run --parallel watch",
-    "clear": "(yarn workspace website clear || echo 'Failure while running docusaurus clear') && yarn lerna exec --ignore docusaurus yarn rimraf lib lib-next",
+    "clear": "(yarn workspace website clear || echo 'Failure while running docusaurus clear') && yarn lerna exec --ignore docusaurus yarn rimraf lib",
     "test:baseUrl": "yarn build:website:baseUrl && yarn serve:website:baseUrl",
     "lock:update": "npx yarn-deduplicate"
   },
diff --git a/packages/docusaurus-theme-classic/.npmignore b/packages/docusaurus-theme-classic/.npmignore
index 955841b312..03c9ae1e1b 100644
--- a/packages/docusaurus-theme-classic/.npmignore
+++ b/packages/docusaurus-theme-classic/.npmignore
@@ -1,9 +1,3 @@
 .tsbuildinfo*
 tsconfig*
 __tests__
-
-lib/theme
-lib-next/**
-!lib-next/theme/**
-
-babel.config.js
diff --git a/packages/docusaurus-theme-classic/babel.config.js b/packages/docusaurus-theme-classic/babel.config.js
deleted file mode 100644
index 0bbcfe267e..0000000000
--- a/packages/docusaurus-theme-classic/babel.config.js
+++ /dev/null
@@ -1,30 +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.
- */
-
-module.exports = {
-  env: {
-    // USED FOR NODE/RUNTIME
-    // maybe we should differentiate both cases because
-    // we mostly need to transpile some features so that node does not crash...
-    lib: {
-      presets: [
-        ['@babel/preset-env', {targets: {node: 14}, modules: 'commonjs'}],
-        ['@babel/preset-typescript', {isTSX: true, allExtensions: true}],
-      ],
-    },
-
-    // USED FOR JS SWIZZLE
-    // /lib-next folder is used as source to swizzle JS source code
-    // This JS code is created from TS source code
-    // This source code should look clean/human readable to be usable
-    'lib-next': {
-      presets: [
-        ['@babel/preset-typescript', {isTSX: true, allExtensions: true}],
-      ],
-    },
-  },
-};
diff --git a/packages/docusaurus-theme-classic/package.json b/packages/docusaurus-theme-classic/package.json
index bcbdb78c31..15810bc398 100644
--- a/packages/docusaurus-theme-classic/package.json
+++ b/packages/docusaurus-theme-classic/package.json
@@ -14,13 +14,10 @@
   },
   "license": "MIT",
   "scripts": {
-    "build": "tsc --noEmit && yarn babel:lib && yarn babel:lib-next && yarn format:lib-next",
-    "watch": "run-p --continue-on-error babel:lib:watch babel:lib-next:watch",
-    "babel:lib": "cross-env BABEL_ENV=lib babel src -d lib --extensions \".tsx,.ts\" --ignore \"**/*.d.ts\" --copy-files",
-    "babel:lib-next": "cross-env BABEL_ENV=lib-next babel src -d lib-next --extensions \".tsx,.ts\" --ignore \"**/*.d.ts\" --copy-files",
-    "babel:lib:watch": "yarn babel:lib --watch",
-    "babel:lib-next:watch": "yarn babel:lib-next --watch",
-    "format:lib-next": "prettier --config ../../.prettierrc --write \"lib-next/**/*.{js,ts,jsx,tsc}\""
+    "build": "tsc --build && node ../../admin/scripts/copyUntypedFiles.mjs && prettier --config ../../.prettierrc --write \"lib/theme/**/*.js\"",
+    "watch": "run-p -c copy:watch build:watch",
+    "build:watch": "tsc --build --watch",
+    "copy:watch": "node ../../admin/scripts/copyUntypedFiles.mjs --watch"
   },
   "dependencies": {
     "@docusaurus/core": "2.0.0-beta.20",
@@ -42,19 +39,16 @@
     "prism-react-renderer": "^1.3.3",
     "prismjs": "^1.28.0",
     "react-router-dom": "^5.2.0",
-    "rtlcss": "^3.5.0"
+    "rtlcss": "^3.5.0",
+    "tslib": "^2.4.0"
   },
   "devDependencies": {
-    "@babel/cli": "^7.17.10",
-    "@babel/core": "^7.17.12",
-    "@babel/preset-typescript": "^7.17.12",
     "@docusaurus/module-type-aliases": "2.0.0-beta.20",
     "@docusaurus/types": "2.0.0-beta.20",
     "@types/mdx-js__react": "^1.5.5",
     "@types/nprogress": "^0.2.0",
     "@types/prismjs": "^1.26.0",
     "@types/rtlcss": "^3.1.4",
-    "cross-env": "^7.0.3",
     "fs-extra": "^10.1.0",
     "react-test-renderer": "^17.0.2",
     "utility-types": "^3.10.0"
diff --git a/packages/docusaurus-theme-classic/src/index.ts b/packages/docusaurus-theme-classic/src/index.ts
index 2624572016..a0cb4629cb 100644
--- a/packages/docusaurus-theme-classic/src/index.ts
+++ b/packages/docusaurus-theme-classic/src/index.ts
@@ -112,7 +112,7 @@ export default function themeClassic(
     name: 'docusaurus-theme-classic',
 
     getThemePath() {
-      return '../lib-next/theme';
+      return '../lib/theme';
     },
 
     getTypeScriptThemePath() {
diff --git a/packages/docusaurus-theme-classic/tsconfig.client.json b/packages/docusaurus-theme-classic/tsconfig.client.json
new file mode 100644
index 0000000000..067fb209a7
--- /dev/null
+++ b/packages/docusaurus-theme-classic/tsconfig.client.json
@@ -0,0 +1,20 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "noEmit": false,
+    "composite": true,
+    "incremental": true,
+    "tsBuildInfoFile": "./lib/.tsbuildinfo-client",
+    "rootDir": "src",
+    "outDir": "lib",
+    "module": "esnext",
+    "target": "esnext"
+  },
+  "include": [
+    "src/nprogress.ts",
+    "src/prism-include-languages.ts",
+    "src/theme",
+    "src/*.d.ts"
+  ],
+  "exclude": ["**/__tests__/**"]
+}
diff --git a/packages/docusaurus-theme-classic/tsconfig.json b/packages/docusaurus-theme-classic/tsconfig.json
index 4ee40b287f..9e41ec3ef6 100644
--- a/packages/docusaurus-theme-classic/tsconfig.json
+++ b/packages/docusaurus-theme-classic/tsconfig.json
@@ -1,10 +1,19 @@
 {
   "extends": "../../tsconfig.json",
+  "references": [{"path": "./tsconfig.client.json"}],
   "compilerOptions": {
-    "lib": ["DOM", "ES2019"],
-    "module": "esnext",
-    "noEmit": true
+    "noEmit": false,
+    "incremental": true,
+    "tsBuildInfoFile": "./lib/.tsbuildinfo",
+    "module": "commonjs",
+    "rootDir": "src",
+    "outDir": "lib"
   },
-  "include": ["src/"],
-  "exclude": ["**/__tests__/**"]
+  "include": ["src"],
+  "exclude": [
+    "src/nprogress.ts",
+    "src/prism-include-languages.ts",
+    "src/theme",
+    "**/__tests__/**"
+  ]
 }
diff --git a/packages/docusaurus-theme-translations/src/utils.ts b/packages/docusaurus-theme-translations/src/utils.ts
index beb1370817..da931ef454 100644
--- a/packages/docusaurus-theme-translations/src/utils.ts
+++ b/packages/docusaurus-theme-translations/src/utils.ts
@@ -25,10 +25,7 @@ async function getPackageCodePath(packageName: string) {
   const packageJsonPath = path.join(packagePath, 'package.json');
   const {main} = await fs.readJSON(packageJsonPath);
   const packageSrcPath = path.join(packagePath, path.dirname(main));
-  const packageLibNextPath = packageSrcPath.replace('lib', 'lib-next');
-  return (await fs.pathExists(packageLibNextPath))
-    ? packageLibNextPath
-    : packageSrcPath;
+  return packageSrcPath;
 }
 
 export async function getThemes(): Promise<{name: string; src: string[]}[]> {
diff --git a/website/_dogfooding/testSwizzleThemeClassic.mjs b/website/_dogfooding/testSwizzleThemeClassic.mjs
index b8b4a4cb1a..ab75a7d1da 100644
--- a/website/_dogfooding/testSwizzleThemeClassic.mjs
+++ b/website/_dogfooding/testSwizzleThemeClassic.mjs
@@ -31,7 +31,7 @@ const classicThemePathBase = path.join(
 
 const themePath = swizzleConfig
   ? path.join(classicThemePathBase, 'src/theme')
-  : path.join(classicThemePathBase, 'lib-next/theme');
+  : path.join(classicThemePathBase, 'lib/theme');
 
 const toPath = path.join(dirname, '_swizzle_theme_tests');
 
diff --git a/yarn.lock b/yarn.lock
index 73710442ca..769b532fb0 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -147,22 +147,6 @@
     jsonpointer "^5.0.0"
     leven "^3.1.0"
 
-"@babel/cli@^7.17.10":
-  version "7.17.10"
-  resolved "https://registry.yarnpkg.com/@babel/cli/-/cli-7.17.10.tgz#5ea0bf6298bb78f3b59c7c06954f9bd1c79d5943"
-  integrity sha512-OygVO1M2J4yPMNOW9pb+I6kFGpQK77HmG44Oz3hg8xQIl5L/2zq+ZohwAdSaqYgVwM0SfmPHZHphH4wR8qzVYw==
-  dependencies:
-    "@jridgewell/trace-mapping" "^0.3.8"
-    commander "^4.0.1"
-    convert-source-map "^1.1.0"
-    fs-readdir-recursive "^1.1.0"
-    glob "^7.0.0"
-    make-dir "^2.1.0"
-    slash "^2.0.0"
-  optionalDependencies:
-    "@nicolo-ribaudo/chokidar-2" "2.1.8-no-fsevents.3"
-    chokidar "^3.4.0"
-
 "@babel/code-frame@^7.0.0", "@babel/code-frame@^7.10.4", "@babel/code-frame@^7.12.13", "@babel/code-frame@^7.16.0", "@babel/code-frame@^7.16.7", "@babel/code-frame@^7.8.3":
   version "7.16.7"
   resolved "https://registry.yarnpkg.com/@babel/code-frame/-/code-frame-7.16.7.tgz#44416b6bd7624b998f5b1af5d470856c40138789"
@@ -1872,7 +1856,7 @@
   resolved "https://registry.yarnpkg.com/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.4.13.tgz#b6461fb0c2964356c469e115f504c95ad97ab88c"
   integrity sha512-GryiOJmNcWbovBxTfZSF71V/mXbgcV3MewDe3kIMCLyIh5e7SKAeUZs+rMnJ8jkMolZ/4/VsdBmMrw3l+VdZ3w==
 
-"@jridgewell/trace-mapping@^0.3.7", "@jridgewell/trace-mapping@^0.3.8", "@jridgewell/trace-mapping@^0.3.9":
+"@jridgewell/trace-mapping@^0.3.7", "@jridgewell/trace-mapping@^0.3.9":
   version "0.3.13"
   resolved "https://registry.yarnpkg.com/@jridgewell/trace-mapping/-/trace-mapping-0.3.13.tgz#dcfe3e95f224c8fe97a87a5235defec999aa92ea"
   integrity sha512-o1xbKhp9qnIAoHJSWd6KlCZfqslL4valSF81H8ImioOAxluWYWOpWkpyktY2vnt4tbrX9XYaxovq6cgowaJp2w==
@@ -2611,11 +2595,6 @@
   dependencies:
     is-promise "^4.0.0"
 
-"@nicolo-ribaudo/chokidar-2@2.1.8-no-fsevents.3":
-  version "2.1.8-no-fsevents.3"
-  resolved "https://registry.yarnpkg.com/@nicolo-ribaudo/chokidar-2/-/chokidar-2-2.1.8-no-fsevents.3.tgz#323d72dd25103d0c4fbdce89dadf574a787b1f9b"
-  integrity sha512-s88O1aVtXftvp5bCPB7WnmXc5IwOZZ7YPuwNPt+GtOOXpPvad1LfbmjYv+qII7zP6RU2QGnqve27dnLycEnyEQ==
-
 "@nodelib/fs.scandir@2.1.5":
   version "2.1.5"
   resolved "https://registry.yarnpkg.com/@nodelib/fs.scandir/-/fs.scandir-2.1.5.tgz#7619c2eb21b25483f6d167548b4cfd5a7488c3d5"
@@ -5219,7 +5198,7 @@ cheerio@^1.0.0-rc.10:
     parse5-htmlparser2-tree-adapter "^6.0.1"
     tslib "^2.2.0"
 
-chokidar@^3.4.0, chokidar@^3.4.2, chokidar@^3.5.3:
+chokidar@^3.4.2, chokidar@^3.5.3:
   version "3.5.3"
   resolved "https://registry.yarnpkg.com/chokidar/-/chokidar-3.5.3.tgz#1cf37c8707b932bd1af1ae22c0432e2acd1903bd"
   integrity sha512-Dr3sfKRP6oTcjf2JmUmFJfeVMvXBdegxB0iVQ5eb2V10uFJUCAS8OByZdVAyVb8xXNz3GjjTgj9kLWsZTqE6kw==
@@ -5520,11 +5499,6 @@ commander@^2.20.0:
   resolved "https://registry.yarnpkg.com/commander/-/commander-2.20.3.tgz#fd485e84c03eb4881c20722ba48035e8531aeb33"
   integrity sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ==
 
-commander@^4.0.1:
-  version "4.1.1"
-  resolved "https://registry.yarnpkg.com/commander/-/commander-4.1.1.tgz#9fd602bd936294e9e9ef46a3f4d6964044b18068"
-  integrity sha512-NOKm8xhkzAjzFx8B2v5OAHT+u5pRQc2UCa2Vq9jYL/31o2wi9mxBA7LIFs3sV5VSC49z6pEhfbMULvShKj26WA==
-
 commander@^5.0.0, commander@^5.1.0:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/commander/-/commander-5.1.0.tgz#46abbd1652f8e059bddaef99bbdcb2ad9cf179ae"
@@ -5773,7 +5747,7 @@ conventional-recommended-bump@^6.1.0:
     meow "^8.0.0"
     q "^1.5.1"
 
-convert-source-map@^1.1.0, convert-source-map@^1.4.0, convert-source-map@^1.6.0, convert-source-map@^1.7.0:
+convert-source-map@^1.4.0, convert-source-map@^1.6.0, convert-source-map@^1.7.0:
   version "1.8.0"
   resolved "https://registry.yarnpkg.com/convert-source-map/-/convert-source-map-1.8.0.tgz#f3373c32d21b4d780dd8004514684fb791ca4369"
   integrity sha512-+OQdjP49zViI/6i7nIJpA8rAl4sV/JdPfU9nZs3VqOwGIgizICvuN2ru6fMd+4llL0tar18UYJXfZ/TWtmhUjA==
@@ -7615,11 +7589,6 @@ fs-monkey@1.0.3:
   resolved "https://registry.yarnpkg.com/fs-monkey/-/fs-monkey-1.0.3.tgz#ae3ac92d53bb328efe0e9a1d9541f6ad8d48e2d3"
   integrity sha512-cybjIfiiE+pTWicSCLFHSrXZ6EilF30oh91FDP9S2B051prEa7QWfrVTQm10/dDpswBDXZugPa1Ogu8Yh+HV0Q==
 
-fs-readdir-recursive@^1.1.0:
-  version "1.1.0"
-  resolved "https://registry.yarnpkg.com/fs-readdir-recursive/-/fs-readdir-recursive-1.1.0.tgz#e32fc030a2ccee44a6b5371308da54be0b397d27"
-  integrity sha512-GNanXlVr2pf02+sPN40XN8HG+ePaNcvM0q5mZBd668Obwb0yD5GiUbZOFgwn8kGMY6I3mdyDJzieUy3PTYyTRA==
-
 fs.realpath@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/fs.realpath/-/fs.realpath-1.0.0.tgz#1504ad2523158caa40db4a2787cb01411994ea4f"
@@ -13670,11 +13639,6 @@ sitemap@^7.1.1:
     arg "^5.0.0"
     sax "^1.2.4"
 
-slash@^2.0.0:
-  version "2.0.0"
-  resolved "https://registry.yarnpkg.com/slash/-/slash-2.0.0.tgz#de552851a1759df3a8f206535442f5ec4ddeab44"
-  integrity sha512-ZYKh3Wh2z1PpEXWr0MpSBZ0V6mZHAQfYevttO11c51CaWjGTaadiKZ+wVt1PbMlDV5qhMFslpZCemhwOK7C89A==
-
 slash@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/slash/-/slash-3.0.0.tgz#6539be870c165adbd5240220dbe361f1bc4d4634"