diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index a0f89301d..abd521300 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -176,10 +176,7 @@ module.exports = {
     {
       files: [
         "**/*.cjs",
-        "src/common/**/*.js",
-        "src/config/**/*.js",
         "src/document/**/*.js",
-        "src/main/**/*.js",
         "src/utils/**/*.js",
         "scripts/tools/eslint-plugin-prettier-internal-rules/**/*.js",
         "website/**/*.js",
diff --git a/scripts/build/bundler.mjs b/scripts/build/bundler.mjs
index 6ddc3aae5..93b4a09ed 100644
--- a/scripts/build/bundler.mjs
+++ b/scripts/build/bundler.mjs
@@ -77,6 +77,11 @@ function* getEsbuildOptions(bundle, buildOptions) {
         };
       }
     }
+
+    // Use `__dirname` directly
+    replaceStrings[
+      "const __dirname = path.dirname(fileURLToPath(import.meta.url));"
+    ] = "";
   } else {
     // Universal bundle only use version info from package.json
     // Replace package.json with `{version: "{VERSION}"}`
diff --git a/scripts/build/config.mjs b/scripts/build/config.mjs
index 045a64ecf..2bb07e4c1 100644
--- a/scripts/build/config.mjs
+++ b/scripts/build/config.mjs
@@ -214,7 +214,8 @@ const coreBundles = [
     external: ["benchmark"],
   },
   {
-    input: "src/common/third-party.js",
+    input: "src/common/third-party.cjs",
+    output: "third-party.js",
     replace: {
       // cosmiconfig@6 -> import-fresh can't find parentModule, since module is bundled
       "parentModule(__filename)": "__filename",
diff --git a/src/cli/format.js b/src/cli/format.js
index 7ff3c603e..657005524 100644
--- a/src/cli/format.js
+++ b/src/cli/format.js
@@ -2,7 +2,7 @@ import { promises as fs } from "fs";
 import path from "path";
 import chalk from "chalk";
 import prettier from "../index.js";
-import thirdParty from "../common/third-party.js";
+import thirdParty from "../common/third-party.cjs";
 import prettierInternal from "./prettier-internal.js";
 import { expandPatterns, fixWindowsSlashes } from "./expand-patterns.js";
 import getOptionsForFile from "./options/get-options-for-file.js";
diff --git a/src/cli/is-tty.js b/src/cli/is-tty.js
index 0379c61ba..64c37e82e 100644
--- a/src/cli/is-tty.js
+++ b/src/cli/is-tty.js
@@ -1,4 +1,4 @@
-import thirdParty from "../common/third-party.js";
+import thirdParty from "../common/third-party.cjs";
 
 // Some CI pipelines incorrectly report process.stdout.isTTY status,
 // which causes unwanted lines in the output. An additional check for isCI() helps.
diff --git a/src/common/ast-path.js b/src/common/ast-path.js
index ade4952a1..eef2b6402 100644
--- a/src/common/ast-path.js
+++ b/src/common/ast-path.js
@@ -1,5 +1,4 @@
-"use strict";
-const getLast = require("../utils/get-last.js");
+import getLast from "../utils/get-last.js";
 
 function getNodeHelper(path, count) {
   const stackIndex = getNodeStackIndexHelper(path.stack, count);
@@ -194,4 +193,4 @@ class AstPath {
   }
 }
 
-module.exports = AstPath;
+export default AstPath;
diff --git a/src/common/common-options.js b/src/common/common-options.js
index 7fa62085a..6c35eae01 100644
--- a/src/common/common-options.js
+++ b/src/common/common-options.js
@@ -1,9 +1,7 @@
-"use strict";
-
 const CATEGORY_COMMON = "Common";
 
 // format based on https://github.com/prettier/prettier/blob/main/src/main/core-options.js
-module.exports = {
+const options = {
   bracketSpacing: {
     since: "0.0.0",
     category: CATEGORY_COMMON,
@@ -62,3 +60,5 @@ module.exports = {
     description: "Enforce single attribute per line in HTML, Vue and JSX.",
   },
 };
+
+export default options;
diff --git a/src/common/create-ignorer.js b/src/common/create-ignorer.js
index 4ccfc4121..b7c7ade6b 100644
--- a/src/common/create-ignorer.js
+++ b/src/common/create-ignorer.js
@@ -1,8 +1,6 @@
-"use strict";
-
-const path = require("path");
-const ignore = require("ignore");
-const getFileContentOrNull = require("../utils/get-file-content-or-null.js");
+import path from "path";
+import ignore from "ignore";
+import getFileContentOrNull from "../utils/get-file-content-or-null.js";
 
 /**
  * @param {string?} ignorePath
@@ -39,4 +37,4 @@ function _createIgnorer(ignoreContent, withNodeModules) {
   return ignorer;
 }
 
-module.exports = createIgnorer;
+export default createIgnorer;
diff --git a/src/common/end-of-line.cjs b/src/common/end-of-line.cjs
new file mode 100644
index 000000000..0c6365a28
--- /dev/null
+++ b/src/common/end-of-line.cjs
@@ -0,0 +1,54 @@
+// cjs version for ../doc to use
+"use strict";
+
+function guessEndOfLine(text) {
+  const index = text.indexOf("\r");
+  if (index >= 0) {
+    return text.charAt(index + 1) === "\n" ? "crlf" : "cr";
+  }
+  return "lf";
+}
+
+function convertEndOfLineToChars(value) {
+  switch (value) {
+    case "cr":
+      return "\r";
+    case "crlf":
+      return "\r\n";
+    default:
+      return "\n";
+  }
+}
+
+function countEndOfLineChars(text, eol) {
+  let regex;
+
+  switch (eol) {
+    case "\n":
+      regex = /\n/g;
+      break;
+    case "\r":
+      regex = /\r/g;
+      break;
+    case "\r\n":
+      regex = /\r\n/g;
+      break;
+    default:
+      /* istanbul ignore next */
+      throw new Error(`Unexpected "eol" ${JSON.stringify(eol)}.`);
+  }
+
+  const endOfLines = text.match(regex);
+  return endOfLines ? endOfLines.length : 0;
+}
+
+function normalizeEndOfLine(text) {
+  return text.replace(/\r\n?/g, "\n");
+}
+
+module.exports = {
+  guessEndOfLine,
+  convertEndOfLineToChars,
+  countEndOfLineChars,
+  normalizeEndOfLine,
+};
diff --git a/src/common/end-of-line.js b/src/common/end-of-line.js
index 994443c59..84b7c9ecd 100644
--- a/src/common/end-of-line.js
+++ b/src/common/end-of-line.js
@@ -1,5 +1,3 @@
-"use strict";
-
 function guessEndOfLine(text) {
   const index = text.indexOf("\r");
   if (index >= 0) {
@@ -45,7 +43,7 @@ function normalizeEndOfLine(text) {
   return text.replace(/\r\n?/g, "\n");
 }
 
-module.exports = {
+export {
   guessEndOfLine,
   convertEndOfLineToChars,
   countEndOfLineChars,
diff --git a/src/common/errors.js b/src/common/errors.js
index 60979117b..bc060690f 100644
--- a/src/common/errors.js
+++ b/src/common/errors.js
@@ -1,13 +1,6 @@
-"use strict";
-
 class ConfigError extends Error {}
 class DebugError extends Error {}
 class UndefinedParserError extends Error {}
 class ArgExpansionBailout extends Error {}
 
-module.exports = {
-  ConfigError,
-  DebugError,
-  UndefinedParserError,
-  ArgExpansionBailout,
-};
+export { ConfigError, DebugError, UndefinedParserError, ArgExpansionBailout };
diff --git a/src/common/get-file-info.js b/src/common/get-file-info.js
index d01d1ee95..4799680b1 100644
--- a/src/common/get-file-info.js
+++ b/src/common/get-file-info.js
@@ -1,9 +1,7 @@
-"use strict";
-
-const path = require("path");
-const options = require("../main/options.js");
-const config = require("../config/resolve-config.js");
-const createIgnorer = require("./create-ignorer.js");
+import path from "path";
+import { inferParser } from "../main/options.js";
+import * as config from "../config/resolve-config.js";
+import createIgnorer from "./create-ignorer.js";
 
 /**
  * @typedef {{ ignorePath?: string, withNodeModules?: boolean, plugins: object }} FileInfoOptions
@@ -65,7 +63,7 @@ function getFileParser(resolvedConfig, filePath, plugins) {
     return resolvedConfig.parser;
   }
 
-  const inferredParser = options.inferParser(filePath, plugins);
+  const inferredParser = inferParser(filePath, plugins);
 
   if (inferredParser) {
     return inferredParser;
@@ -120,4 +118,4 @@ function normalizeFilePath(filePath, ignorePath) {
     : filePath;
 }
 
-module.exports = getFileInfo;
+export default getFileInfo;
diff --git a/src/common/load-plugins.js b/src/common/load-plugins.js
index a70846b85..c34a6e39a 100644
--- a/src/common/load-plugins.js
+++ b/src/common/load-plugins.js
@@ -1,13 +1,16 @@
-"use strict";
+import { createRequire } from "module";
+import fs from "fs";
+import path from "path";
+import { fileURLToPath } from "url";
+import uniqBy from "lodash/uniqBy.js";
+import partition from "lodash/partition.js";
+import fastGlob from "fast-glob";
+import mem, { memClear } from "mem";
+import thirdParty from "./third-party.cjs";
+import resolve from "./resolve.js";
 
-const fs = require("fs");
-const path = require("path");
-const uniqBy = require("lodash/uniqBy.js");
-const partition = require("lodash/partition.js");
-const fastGlob = require("fast-glob");
-const { default: mem, memClear } = require("../../vendors/mem.js");
-const thirdParty = require("./third-party.js");
-const resolve = require("./resolve.js");
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const require = createRequire(import.meta.url);
 
 const memoizedLoad = mem(load, { cacheKey: JSON.stringify });
 const memoizedSearch = mem(findPluginsInNodeModules);
@@ -125,7 +128,4 @@ function isDirectory(dir) {
   }
 }
 
-module.exports = {
-  loadPlugins: memoizedLoad,
-  clearCache,
-};
+export { memoizedLoad as loadPlugins, clearCache };
diff --git a/src/common/package.json b/src/common/package.json
deleted file mode 100644
index 54d221724..000000000
--- a/src/common/package.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "//TODO": "Remove this file when we close #10157",
-  "type": "commonjs",
-  "description": "A package.json file to use `.js` files in this directory as CommonJS module."
-}
diff --git a/src/common/parser-create-error.js b/src/common/parser-create-error.js
index f7ee8e5e1..7416c8fef 100644
--- a/src/common/parser-create-error.js
+++ b/src/common/parser-create-error.js
@@ -1,5 +1,3 @@
-"use strict";
-
 function createError(message, loc) {
   // Construct an error similar to the ones thrown by Babel.
   const error = new SyntaxError(
@@ -10,4 +8,4 @@ function createError(message, loc) {
   return error;
 }
 
-module.exports = createError;
+export default createError;
diff --git a/src/common/resolve.js b/src/common/resolve.js
index 8989edc97..0dd18ec61 100644
--- a/src/common/resolve.js
+++ b/src/common/resolve.js
@@ -1,4 +1,6 @@
-"use strict";
+import { createRequire } from "module";
+
+const require = createRequire(import.meta.url);
 
 let { resolve } = require;
 
@@ -15,4 +17,4 @@ if (resolve.length === 1 || process.env.PRETTIER_FALLBACK_RESOLVE) {
   };
 }
 
-module.exports = resolve;
+export default resolve;
diff --git a/src/common/third-party.js b/src/common/third-party.cjs
similarity index 100%
rename from src/common/third-party.js
rename to src/common/third-party.cjs
diff --git a/src/common/util-shared.js b/src/common/util-shared.js
index 0c03bb731..2d1aa8218 100644
--- a/src/common/util-shared.js
+++ b/src/common/util-shared.js
@@ -1,6 +1,4 @@
-"use strict";
-
-const {
+export {
   getMaxContinuousCount,
   getStringWidth,
   getAlignmentSize,
@@ -24,30 +22,4 @@ const {
   addLeadingComment,
   addDanglingComment,
   addTrailingComment,
-} = require("./util.js");
-
-module.exports = {
-  getMaxContinuousCount,
-  getStringWidth,
-  getAlignmentSize,
-  getIndentSize,
-  skip,
-  skipWhitespace,
-  skipSpaces,
-  skipNewline,
-  skipToLineEnd,
-  skipEverythingButNewLine,
-  skipInlineComment,
-  skipTrailingComment,
-  hasNewline,
-  hasNewlineInRange,
-  hasSpaces,
-  isNextLineEmpty,
-  isNextLineEmptyAfterIndex,
-  isPreviousLineEmpty,
-  getNextNonSpaceNonCommentCharacterIndex,
-  makeString,
-  addLeadingComment,
-  addDanglingComment,
-  addTrailingComment,
-};
+} from "./util.js";
diff --git a/src/common/util.js b/src/common/util.js
index 4acfb14d9..3a1604641 100644
--- a/src/common/util.js
+++ b/src/common/util.js
@@ -1,20 +1,18 @@
-"use strict";
-
-const escapeStringRegexp = require("escape-string-regexp");
-const getLast = require("../utils/get-last.js");
-const { getSupportInfo } = require("../main/support.js");
-const isNonEmptyArray = require("../utils/is-non-empty-array.js");
-const getStringWidth = require("../utils/get-string-width.js");
-const {
+import escapeStringRegexp from "escape-string-regexp";
+import getLast from "../utils/get-last.js";
+import { getSupportInfo } from "../main/support.js";
+import isNonEmptyArray from "../utils/is-non-empty-array.js";
+import getStringWidth from "../utils/get-string-width.js";
+import {
   skipWhitespace,
   skipSpaces,
   skipToLineEnd,
   skipEverythingButNewLine,
-} = require("../utils/text/skip.js");
-const skipInlineComment = require("../utils/text/skip-inline-comment.js");
-const skipTrailingComment = require("../utils/text/skip-trailing-comment.js");
-const skipNewline = require("../utils/text/skip-newline.js");
-const getNextNonSpaceNonCommentCharacterIndexWithStartIndex = require("../utils/text/get-next-non-space-non-comment-character-index-with-start-index.js");
+} from "../utils/text/skip.js";
+import skipInlineComment from "../utils/text/skip-inline-comment.js";
+import skipTrailingComment from "../utils/text/skip-trailing-comment.js";
+import skipNewline from "../utils/text/skip-newline.js";
+import getNextNonSpaceNonCommentCharacterIndexWithStartIndex from "../utils/text/get-next-non-space-non-comment-character-index-with-start-index.js";
 
 const getPenultimate = (arr) => arr[arr.length - 2];
 
@@ -479,7 +477,7 @@ function describeNodeForDebugging(node) {
   return nodeType + (nodeName ? " " + nodeName : "");
 }
 
-module.exports = {
+export {
   inferParserByLanguage,
   getStringWidth,
   getMaxContinuousCount,
diff --git a/src/config/find-project-root.js b/src/config/find-project-root.js
index 10ca7faeb..011c224c3 100644
--- a/src/config/find-project-root.js
+++ b/src/config/find-project-root.js
@@ -1,10 +1,8 @@
-"use strict";
-
 // Simple version of `find-project-root`
 // https://github.com/kirstein/find-project-root/blob/master/index.js
 
-const fs = require("fs");
-const path = require("path");
+import fs from "fs";
+import path from "path";
 
 const MARKERS = [".git", ".hg"];
 
@@ -23,4 +21,4 @@ function findProjectRoot(directory) {
   return directory;
 }
 
-module.exports = findProjectRoot;
+export default findProjectRoot;
diff --git a/src/config/package.json b/src/config/package.json
deleted file mode 100644
index 54d221724..000000000
--- a/src/config/package.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "//TODO": "Remove this file when we close #10157",
-  "type": "commonjs",
-  "description": "A package.json file to use `.js` files in this directory as CommonJS module."
-}
diff --git a/src/config/resolve-config-editorconfig.js b/src/config/resolve-config-editorconfig.js
index e7db00d1c..df790dc30 100644
--- a/src/config/resolve-config-editorconfig.js
+++ b/src/config/resolve-config-editorconfig.js
@@ -1,11 +1,9 @@
-"use strict";
+import path from "path";
 
-const path = require("path");
-
-const editorconfig = require("editorconfig");
-const editorConfigToPrettier = require("editorconfig-to-prettier");
-const { default: mem, memClear } = require("../../vendors/mem.js");
-const findProjectRoot = require("./find-project-root.js");
+import editorconfig from "editorconfig";
+import editorConfigToPrettier from "editorconfig-to-prettier";
+import mem, { memClear } from "mem";
+import findProjectRoot from "./find-project-root.js";
 
 const jsonStringifyMem = (fn) => mem(fn, { cacheKey: JSON.stringify });
 
@@ -40,7 +38,4 @@ function clearCache() {
   memClear(editorconfigAsyncWithCache);
 }
 
-module.exports = {
-  getLoadFunction,
-  clearCache,
-};
+export { getLoadFunction, clearCache };
diff --git a/src/config/resolve-config.js b/src/config/resolve-config.js
index 560ac428e..366232cea 100644
--- a/src/config/resolve-config.js
+++ b/src/config/resolve-config.js
@@ -1,14 +1,13 @@
-"use strict";
+import { createRequire } from "module";
+import path from "path";
+import micromatch from "micromatch";
+import mem, { memClear } from "mem";
+import thirdParty from "../common/third-party.cjs";
 
-const path = require("path");
-const micromatch = require("micromatch");
-const thirdParty = require("../common/third-party.js");
-
-const loadToml = require("../utils/load-toml.js");
-const loadJson5 = require("../utils/load-json5.js");
-const resolve = require("../common/resolve.js");
-const { default: mem, memClear } = require("../../vendors/mem.js");
-const resolveEditorConfig = require("./resolve-config-editorconfig.js");
+import loadToml from "../utils/load-toml.js";
+import loadJson5 from "../utils/load-json5.js";
+import resolve from "../common/resolve.js";
+import * as resolveEditorConfig from "./resolve-config-editorconfig.js";
 
 /**
  * @typedef {import("cosmiconfig/dist/Explorer").Explorer} Explorer
@@ -20,6 +19,7 @@ const resolveEditorConfig = require("./resolve-config-editorconfig.js");
  */
 const getExplorerMemoized = mem(
   (opts) => {
+    const require = createRequire(import.meta.url);
     const cosmiconfig = thirdParty["cosmiconfig" + (opts.sync ? "Sync" : "")];
     const explorer = cosmiconfig("prettier", {
       cache: opts.cache,
@@ -192,8 +192,4 @@ function pathMatchesGlobs(filePath, patterns, excludedPatterns) {
   );
 }
 
-module.exports = {
-  resolveConfig,
-  resolveConfigFile,
-  clearCache,
-};
+export { resolveConfig, resolveConfigFile, clearCache };
diff --git a/src/document/doc-printer.js b/src/document/doc-printer.js
index 1a45f78c6..a8e422178 100644
--- a/src/document/doc-printer.js
+++ b/src/document/doc-printer.js
@@ -1,6 +1,6 @@
 "use strict";
 
-const { convertEndOfLineToChars } = require("../common/end-of-line.js");
+const { convertEndOfLineToChars } = require("../common/end-of-line.cjs");
 const getLast = require("../utils/get-last.js");
 const getStringWidth = require("../utils/get-string-width.js");
 const { fill, cursor, indent } = require("./doc-builders.js");
diff --git a/src/index.js b/src/index.js
index dcdc496ba..bf0719b70 100644
--- a/src/index.js
+++ b/src/index.js
@@ -2,12 +2,28 @@ import { createRequire } from "module";
 import core from "./main/core.js";
 import { getSupportInfo } from "./main/support.js";
 import getFileInfo from "./common/get-file-info.js";
-import sharedUtil from "./common/util-shared.js";
-import plugins from "./common/load-plugins.js";
-import config from "./config/resolve-config.js";
+import * as sharedUtil from "./common/util-shared.js";
+import {
+  loadPlugins,
+  clearCache as clearPluginCache,
+} from "./common/load-plugins.js";
+import {
+  resolveConfig,
+  resolveConfigFile,
+  clearCache as clearConfigCache,
+} from "./config/resolve-config.js";
 import doc from "./document/index.js";
 import languages from "./languages.js";
 
+import * as errors from "./common/errors.js";
+import * as coreOptions from "./main/core-options.js";
+import createIgnorer from "./common/create-ignorer.js";
+import * as optionsModule from "./main/options.js";
+import * as optionsNormalizer from "./main/options-normalizer.js";
+import arrayify from "./utils/arrayify.js";
+import getLast from "./utils/get-last.js";
+import { isNonEmptyArray } from "./common/util.js";
+
 const require = createRequire(import.meta.url);
 
 const { version } = require("../package.json");
@@ -22,7 +38,7 @@ function _withPlugins(
       ...opts,
       plugins: [
         ...languages,
-        ...plugins.loadPlugins(opts.plugins, opts.pluginSearchDirs),
+        ...loadPlugins(opts.plugins, opts.pluginSearchDirs),
       ],
     };
     return fn(...args);
@@ -54,11 +70,11 @@ const prettier = {
 
   doc,
 
-  resolveConfig: config.resolveConfig,
-  resolveConfigFile: config.resolveConfigFile,
+  resolveConfig,
+  resolveConfigFile,
   clearConfigCache() {
-    config.clearCache();
-    plugins.clearCache();
+    clearConfigCache();
+    clearPluginCache();
   },
 
   /** @type {typeof getFileInfo} */
@@ -72,15 +88,15 @@ const prettier = {
 
   // Internal shared
   __internal: {
-    errors: require("./common/errors.js"),
-    coreOptions: require("./main/core-options.js"),
-    createIgnorer: require("./common/create-ignorer.js"),
-    optionsModule: require("./main/options.js"),
-    optionsNormalizer: require("./main/options-normalizer.js"),
+    errors,
+    coreOptions,
+    createIgnorer,
+    optionsModule,
+    optionsNormalizer,
     utils: {
-      arrayify: require("./utils/arrayify.js"),
-      getLast: require("./utils/get-last.js"),
-      isNonEmptyArray: require("./common/util.js").isNonEmptyArray,
+      arrayify,
+      getLast,
+      isNonEmptyArray,
     },
   },
 
diff --git a/src/language-html/utils/index.js b/src/language-html/utils/index.js
index d932c3eb4..355b49e92 100644
--- a/src/language-html/utils/index.js
+++ b/src/language-html/utils/index.js
@@ -1,5 +1,5 @@
 /**
- * @typedef {import("../../common/ast-path")} AstPath
+ * @typedef {import("../../common/ast-path.js").default} AstPath
  */
 
 import { inferParserByLanguage, isFrontMatterNode } from "../../common/util.js";
diff --git a/src/language-js/comments.js b/src/language-js/comments.js
index 2bf77d630..b53acb3ce 100644
--- a/src/language-js/comments.js
+++ b/src/language-js/comments.js
@@ -33,7 +33,7 @@ import isBlockComment from "./utils/is-block-comment.js";
 /**
  * @typedef {import("./types/estree").Node} Node
  * @typedef {import("./types/estree").Comment} Comment
- * @typedef {import("../common/ast-path")} AstPath
+ * @typedef {import("../common/ast-path.js").default} AstPath
  *
  * @typedef {Object} CommentContext
  * @property {Comment} comment
diff --git a/src/language-js/loc.cjs b/src/language-js/loc.cjs
deleted file mode 100644
index 9d1be4f6f..000000000
--- a/src/language-js/loc.cjs
+++ /dev/null
@@ -1,33 +0,0 @@
-// A cjs version of loc.js to use in `../main/parser.js`
-"use strict";
-
-const isNonEmptyArray = require("../utils/is-non-empty-array.js");
-
-/**
- * @typedef {import("./types/estree").Node} Node
- */
-
-function locStart(node, opts) {
-  const { ignoreDecorators } = opts || {};
-
-  // Handle nodes with decorators. They should start at the first decorator
-  if (!ignoreDecorators) {
-    const decorators =
-      (node.declaration && node.declaration.decorators) || node.decorators;
-
-    if (isNonEmptyArray(decorators)) {
-      return locStart(decorators[0]);
-    }
-  }
-
-  return node.range ? node.range[0] : node.start;
-}
-
-function locEnd(node) {
-  return node.range ? node.range[1] : node.end;
-}
-
-module.exports = {
-  locStart,
-  locEnd,
-};
diff --git a/src/language-js/print/angular.js b/src/language-js/print/angular.js
index 1a86c0a6d..85f5c10dd 100644
--- a/src/language-js/print/angular.js
+++ b/src/language-js/print/angular.js
@@ -6,7 +6,7 @@ const {
   builders: { join, line, group },
 } = doc;
 
-/** @typedef {import("../../common/ast-path")} AstPath */
+/** @typedef {import("../../common/ast-path.js").default} AstPath */
 
 function printAngular(path, options, print) {
   const node = path.getValue();
diff --git a/src/language-js/print/jsx.js b/src/language-js/print/jsx.js
index 0a7b55bd2..3ad204bc4 100644
--- a/src/language-js/print/jsx.js
+++ b/src/language-js/print/jsx.js
@@ -36,7 +36,7 @@ const isEmptyStringOrAnyLine = (doc) =>
   doc === "" || doc === line || doc === hardline || doc === softline;
 
 /**
- * @typedef {import("../../common/ast-path")} AstPath
+ * @typedef {import("../../common/ast-path.js").default} AstPath
  * @typedef {import("../types/estree").Node} Node
  * @typedef {import("../types/estree").JSXElement} JSXElement
  */
diff --git a/src/language-js/print/ternary.js b/src/language-js/print/ternary.js
index c8ef1568f..44b1943b2 100644
--- a/src/language-js/print/ternary.js
+++ b/src/language-js/print/ternary.js
@@ -24,7 +24,7 @@ const {
 
 /**
  * @typedef {import("../../document").Doc} Doc
- * @typedef {import("../../common/ast-path")} AstPath
+ * @typedef {import("../../common/ast-path.js").default} AstPath
  *
  * @typedef {any} Options - Prettier options (TBD ...)
  */
diff --git a/src/language-js/utils/index.js b/src/language-js/utils/index.js
index aed479c22..229415241 100644
--- a/src/language-js/utils/index.js
+++ b/src/language-js/utils/index.js
@@ -26,7 +26,7 @@ const isIdentifierName = esutils.keyword.isIdentifierNameES5;
  * @typedef {import("../types/estree").TaggedTemplateExpression} TaggedTemplateExpression
  * @typedef {import("../types/estree").Literal} Literal
  *
- * @typedef {import("../../common/ast-path")} AstPath
+ * @typedef {import("../../common/ast-path.js").default} AstPath
  */
 
 // We match any whitespace except line terminators because
diff --git a/src/main/ast-to-doc.js b/src/main/ast-to-doc.js
index 46d6b8d5d..c8f2280e3 100644
--- a/src/main/ast-to-doc.js
+++ b/src/main/ast-to-doc.js
@@ -1,12 +1,12 @@
-"use strict";
+import AstPath from "../common/ast-path.js";
+import doc from "../document/index.js";
+import { printComments } from "./comments.js";
+import { printSubtree } from "./multiparser.js";
 
-const AstPath = require("../common/ast-path.js");
 const {
   builders: { hardline, addAlignmentToDoc },
   utils: { propagateBreaks },
-} = require("../document/index.js");
-const { printComments } = require("./comments.js");
-const multiparser = require("./multiparser.js");
+} = doc;
 
 /**
  * Takes an abstract syntax tree (AST) and recursively converts it to a
@@ -119,7 +119,7 @@ function callPluginPrintFunction(path, options, printPath, args) {
     if (node) {
       try {
         // Potentially switch to a different parser
-        doc = multiparser.printSubtree(path, printPath, options, printAstToDoc);
+        doc = printSubtree(path, printPath, options, printAstToDoc);
       } catch (error) {
         /* istanbul ignore if */
         if (process.env.PRETTIER_DEBUG) {
@@ -148,4 +148,4 @@ function callPluginPrintFunction(path, options, printPath, args) {
   return doc;
 }
 
-module.exports = printAstToDoc;
+export default printAstToDoc;
diff --git a/src/main/comments.js b/src/main/comments.js
index 77d961586..e860b1b10 100644
--- a/src/main/comments.js
+++ b/src/main/comments.js
@@ -1,12 +1,8 @@
-"use strict";
+import assert from "assert";
 
-const assert = require("assert");
+import doc from "../document/index.js";
 
-const {
-  builders: { line, hardline, breakParent, indent, lineSuffix, join, cursor },
-} = require("../document/index.js");
-
-const {
+import {
   hasNewline,
   skipNewline,
   skipSpaces,
@@ -14,7 +10,11 @@ const {
   addLeadingComment,
   addDanglingComment,
   addTrailingComment,
-} = require("../common/util.js");
+} from "../common/util.js";
+
+const {
+  builders: { line, hardline, breakParent, indent, lineSuffix, join, cursor },
+} = doc;
 
 const childNodesCache = new WeakMap();
 function getSortedChildNodes(node, options, resultArray) {
@@ -601,7 +601,7 @@ function ensureAllCommentsPrinted(astComments) {
   }
 }
 
-module.exports = {
+export {
   attach,
   printComments,
   printCommentsSeparately,
diff --git a/src/main/core-options.js b/src/main/core-options.js
index 5992da931..30587e79c 100644
--- a/src/main/core-options.js
+++ b/src/main/core-options.js
@@ -1,6 +1,4 @@
-"use strict";
-
-const { outdent } = require("outdent");
+import { outdent } from "outdent";
 
 const CATEGORY_CONFIG = "Config";
 const CATEGORY_EDITOR = "Editor";
@@ -266,7 +264,7 @@ const options = {
   },
 };
 
-module.exports = {
+export {
   CATEGORY_CONFIG,
   CATEGORY_EDITOR,
   CATEGORY_FORMAT,
diff --git a/src/main/core.js b/src/main/core.js
index 07e40624f..d6d8fddbb 100644
--- a/src/main/core.js
+++ b/src/main/core.js
@@ -1,25 +1,25 @@
-"use strict";
-
 // Use `diff/lib/diff/array.js` instead of `diff` to reduce bundle size
-const { diffArrays } = require("diff/lib/diff/array.js");
+import { diffArrays } from "diff/lib/diff/array.js";
 
-const {
-  printer: { printDocToString },
-  debug: { printDocToDebug },
-} = require("../document/index.js");
-const { getAlignmentSize } = require("../common/util.js");
-const {
+import doc from "../document/index.js";
+import { getAlignmentSize } from "../common/util.js";
+import {
   guessEndOfLine,
   convertEndOfLineToChars,
   countEndOfLineChars,
   normalizeEndOfLine,
-} = require("../common/end-of-line.js");
-const normalizeOptions = require("./options.js").normalize;
-const massageAST = require("./massage-ast.js");
-const comments = require("./comments.js");
-const parser = require("./parser.js");
-const printAstToDoc = require("./ast-to-doc.js");
-const rangeUtil = require("./range-util.js");
+} from "../common/end-of-line.js";
+import { normalize as normalizeOptions } from "./options.js";
+import massageAST from "./massage-ast.js";
+import { ensureAllCommentsPrinted, attach } from "./comments.js";
+import { parse, resolveParser } from "./parser.js";
+import printAstToDoc from "./ast-to-doc.js";
+import { calculateRange, findNodeAtOffset } from "./range-util.js";
+
+const {
+  printer: { printDocToString },
+  debug: { printDocToDebug },
+} = doc;
 
 const BOM = "\uFEFF";
 
@@ -29,7 +29,7 @@ function attachComments(text, ast, opts) {
   const astComments = ast.comments;
   if (astComments) {
     delete ast.comments;
-    comments.attach(astComments, ast, text, opts);
+    attach(astComments, ast, text, opts);
   }
   opts[Symbol.for("comments")] = astComments || [];
   opts[Symbol.for("tokens")] = ast.tokens || [];
@@ -42,10 +42,10 @@ function coreFormat(originalText, opts, addAlignmentSize = 0) {
     return { formatted: "", cursorOffset: -1, comments: [] };
   }
 
-  const { ast, text } = parser.parse(originalText, opts);
+  const { ast, text } = parse(originalText, opts);
 
   if (opts.cursorOffset >= 0) {
-    const nodeResult = rangeUtil.findNodeAtOffset(ast, opts.cursorOffset, opts);
+    const nodeResult = findNodeAtOffset(ast, opts.cursorOffset, opts);
     if (nodeResult && nodeResult.node) {
       opts.cursorNode = nodeResult.node;
     }
@@ -56,7 +56,7 @@ function coreFormat(originalText, opts, addAlignmentSize = 0) {
 
   const result = printDocToString(doc, opts);
 
-  comments.ensureAllCommentsPrinted(astComments);
+  ensureAllCommentsPrinted(astComments);
   // Remove extra leading indentation as well as the added indentation after last newline
   if (addAlignmentSize > 0) {
     const trimmed = result.formatted.trim();
@@ -146,8 +146,8 @@ function coreFormat(originalText, opts, addAlignmentSize = 0) {
 }
 
 function formatRange(originalText, opts) {
-  const { ast, text } = parser.parse(originalText, opts);
-  const { rangeStart, rangeEnd } = rangeUtil.calculateRange(text, opts, ast);
+  const { ast, text } = parse(originalText, opts);
+  const { rangeStart, rangeEnd } = calculateRange(text, opts, ast);
   const rangeString = text.slice(rangeStart, rangeEnd);
 
   // Try to extend the range backwards to the beginning of the line.
@@ -276,7 +276,7 @@ function normalizeInputAndOptions(text, options) {
 }
 
 function hasPragma(text, options) {
-  const selectedParser = parser.resolveParser(options);
+  const selectedParser = resolveParser(options);
   return !selectedParser.hasPragma || selectedParser.hasPragma(text);
 }
 
@@ -324,7 +324,7 @@ function formatWithCursor(originalText, originalOptions) {
   return result;
 }
 
-module.exports = {
+const prettier = {
   formatWithCursor,
 
   parse(originalText, originalOptions, massage) {
@@ -332,7 +332,7 @@ module.exports = {
       originalText,
       normalizeOptions(originalOptions)
     );
-    const parsed = parser.parse(text, options);
+    const parsed = parse(text, options);
     if (massage) {
       parsed.ast = massageAST(parsed.ast, options);
     }
@@ -355,7 +355,7 @@ module.exports = {
 
   printToDoc(originalText, options) {
     options = normalizeOptions(options);
-    const { ast, text } = parser.parse(originalText, options);
+    const { ast, text } = parse(originalText, options);
     attachComments(text, ast, options);
     return printAstToDoc(ast, options);
   },
@@ -364,3 +364,5 @@ module.exports = {
     return printDocToString(doc, normalizeOptions(options));
   },
 };
+
+export default prettier;
diff --git a/src/main/massage-ast.js b/src/main/massage-ast.js
index 784b568e9..f8dfbe1b7 100644
--- a/src/main/massage-ast.js
+++ b/src/main/massage-ast.js
@@ -1,5 +1,3 @@
-"use strict";
-
 function massageAST(ast, options, parent) {
   if (Array.isArray(ast)) {
     return ast.map((e) => massageAST(e, options, parent)).filter(Boolean);
@@ -37,4 +35,4 @@ function massageAST(ast, options, parent) {
   return newObj;
 }
 
-module.exports = massageAST;
+export default massageAST;
diff --git a/src/main/multiparser.js b/src/main/multiparser.js
index 3af8b24f7..f40c66865 100644
--- a/src/main/multiparser.js
+++ b/src/main/multiparser.js
@@ -1,10 +1,11 @@
-"use strict";
+import doc from "../document/index.js";
+import { normalize } from "./options.js";
+import { ensureAllCommentsPrinted, attach } from "./comments.js";
+import { parse } from "./parser.js";
 
 const {
   utils: { stripTrailingHardline },
-} = require("../document/index.js");
-const { normalize } = require("./options.js");
-const comments = require("./comments.js");
+} = doc;
 
 function printSubtree(path, print, options, printAstToDoc) {
   if (options.printer.embed && options.embeddedLanguageFormatting === "auto") {
@@ -42,18 +43,18 @@ function textToDoc(
     { passThrough: true }
   );
 
-  const result = require("./parser.js").parse(text, nextOptions);
+  const result = parse(text, nextOptions);
   const { ast } = result;
   text = result.text;
 
   const astComments = ast.comments;
   delete ast.comments;
-  comments.attach(astComments, ast, text, nextOptions);
+  attach(astComments, ast, text, nextOptions);
   nextOptions[Symbol.for("comments")] = astComments || [];
   nextOptions[Symbol.for("tokens")] = ast.tokens || [];
 
   const doc = printAstToDoc(ast, nextOptions);
-  comments.ensureAllCommentsPrinted(astComments);
+  ensureAllCommentsPrinted(astComments);
 
   if (shouldStripTrailingHardline) {
     // TODO: move this to `stripTrailingHardline` function in `/src/document/doc-utils.js`
@@ -68,6 +69,4 @@ function textToDoc(
   return doc;
 }
 
-module.exports = {
-  printSubtree,
-};
+export { printSubtree };
diff --git a/src/main/options-normalizer.js b/src/main/options-normalizer.js
index 17742108f..59b1b8c30 100644
--- a/src/main/options-normalizer.js
+++ b/src/main/options-normalizer.js
@@ -1,8 +1,6 @@
-"use strict";
-
-const vnopts = require("vnopts");
-const leven = require("leven");
-const getLast = require("../utils/get-last.js");
+import vnopts from "vnopts";
+import leven from "leven";
+import getLast from "../utils/get-last.js";
 
 const cliDescriptor = {
   key: (key) => (key.length === 1 ? `-${key}` : `--${key}`),
@@ -257,7 +255,4 @@ function normalizeCliOptions(options, optionInfos, opts) {
   return normalizeOptions(options, optionInfos, { isCLI: true, ...opts });
 }
 
-module.exports = {
-  normalizeApiOptions,
-  normalizeCliOptions,
-};
+export { normalizeApiOptions, normalizeCliOptions };
diff --git a/src/main/options.js b/src/main/options.js
index 27f21f7b7..25f213ce4 100644
--- a/src/main/options.js
+++ b/src/main/options.js
@@ -1,10 +1,9 @@
-"use strict";
-
-const path = require("path");
-const { UndefinedParserError } = require("../common/errors.js");
-const { getSupportInfo } = require("../main/support.js");
-const normalizer = require("./options-normalizer.js");
-const { resolveParser } = require("./parser.js");
+import { createRequire } from "module";
+import path from "path";
+import { UndefinedParserError } from "../common/errors.js";
+import { getSupportInfo } from "../main/support.js";
+import { normalizeApiOptions } from "./options-normalizer.js";
+import { resolveParser } from "./parser.js";
 
 const hiddenDefaults = {
   astFormat: "estree",
@@ -52,7 +51,7 @@ function normalize(options, opts = {}) {
   }
 
   const parser = resolveParser(
-    normalizer.normalizeApiOptions(
+    normalizeApiOptions(
       rawOptions,
       [supportOptions.find((x) => x.name === "parser")],
       { passThrough: true, logger: false }
@@ -90,7 +89,7 @@ function normalize(options, opts = {}) {
     rawOptions.trailingComma = "none";
   }
 
-  return normalizer.normalizeApiOptions(rawOptions, supportOptions, {
+  return normalizeApiOptions(rawOptions, supportOptions, {
     passThrough: Object.keys(hiddenDefaults),
     ...opts,
   });
@@ -140,6 +139,7 @@ function inferParser(filepath, plugins) {
     !language &&
     !filename.includes(".")
   ) {
+    const require = createRequire(import.meta.url);
     // `getInterpreter` requires file access, put `require()` in the `if` block,
     // So we can easily remove this part during build
     const getInterpreter = require("../utils/get-interpreter.js");
@@ -153,4 +153,4 @@ function inferParser(filepath, plugins) {
   return language && language.parsers[0];
 }
 
-module.exports = { normalize, hiddenDefaults, inferParser };
+export { normalize, hiddenDefaults, inferParser };
diff --git a/src/main/package.json b/src/main/package.json
deleted file mode 100644
index 54d221724..000000000
--- a/src/main/package.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "//TODO": "Remove this file when we close #10157",
-  "type": "commonjs",
-  "description": "A package.json file to use `.js` files in this directory as CommonJS module."
-}
diff --git a/src/main/parser.js b/src/main/parser.js
index defccccd0..e49d9c75d 100644
--- a/src/main/parser.js
+++ b/src/main/parser.js
@@ -1,11 +1,9 @@
-"use strict";
+import { createRequire } from "module";
+import path from "path";
+import { ConfigError } from "../common/errors.js";
+import { locStart, locEnd } from "../language-js/loc.js";
 
-const path = require("path");
-const { ConfigError } = require("../common/errors.js");
-// TODO: Use esm version
-const jsLoc = require("../language-js/loc.cjs");
-
-const { locStart, locEnd } = jsLoc;
+const require = createRequire(import.meta.url);
 
 // Use defineProperties()/getOwnPropertyDescriptor() to prevent
 // triggering the parsers getters.
@@ -111,4 +109,4 @@ function parse(text, opts) {
   }
 }
 
-module.exports = { parse, resolveParser };
+export { parse, resolveParser };
diff --git a/src/main/range-util.js b/src/main/range-util.js
index ecb396ef1..b6c364cc9 100644
--- a/src/main/range-util.js
+++ b/src/main/range-util.js
@@ -1,7 +1,5 @@
-"use strict";
-
-const assert = require("assert");
-const comments = require("./comments.js");
+import assert from "assert";
+import { getSortedChildNodes } from "./comments.js";
 
 const isJsonParser = ({ parser }) =>
   parser === "json" || parser === "json5" || parser === "json-stringify";
@@ -93,7 +91,7 @@ function findNodeAtOffset(
     return;
   }
 
-  for (const childNode of comments.getSortedChildNodes(node, options)) {
+  for (const childNode of getSortedChildNodes(node, options)) {
     const childResult = findNodeAtOffset(
       childNode,
       offset,
@@ -252,7 +250,4 @@ function calculateRange(text, opts, ast) {
   };
 }
 
-module.exports = {
-  calculateRange,
-  findNodeAtOffset,
-};
+export { calculateRange, findNodeAtOffset };
diff --git a/src/main/support.js b/src/main/support.js
index 6bf3ad8d8..5eb258b0b 100644
--- a/src/main/support.js
+++ b/src/main/support.js
@@ -1,13 +1,13 @@
-"use strict";
+import { createRequire } from "module";
+import semverCompare from "semver/functions/compare.js";
+import semverGte from "semver/functions/gte.js";
+import semverLt from "semver/functions/lt.js";
+import arrayify from "../utils/arrayify.js";
+import { options as coreOptions } from "./core-options.js";
+
+const require = createRequire(import.meta.url);
 
-const semver = {
-  compare: require("semver/functions/compare"),
-  lt: require("semver/functions/lt"),
-  gte: require("semver/functions/gte"),
-};
-const arrayify = require("../utils/arrayify.js");
 const currentVersion = require("../../package.json").version;
-const coreOptions = require("./core-options.js").options;
 
 /**
  * Strings in `plugins` and `pluginSearchDirs` are handled by a wrapped version
@@ -50,7 +50,7 @@ function getSupportInfo({
             : option.default
                 .filter(filterSince)
                 .sort((info1, info2) =>
-                  semver.compare(info2.since, info1.since)
+                  semverCompare(info2.since, info1.since)
                 )[0].value;
       }
 
@@ -83,7 +83,7 @@ function getSupportInfo({
     return (
       showUnreleased ||
       !("since" in object) ||
-      (object.since && semver.gte(version, object.since))
+      (object.since && semverGte(version, object.since))
     );
   }
 
@@ -91,7 +91,7 @@ function getSupportInfo({
     return (
       showDeprecated ||
       !("deprecated" in object) ||
-      (object.deprecated && semver.lt(version, object.deprecated))
+      (object.deprecated && semverLt(version, object.deprecated))
     );
   }
 
@@ -125,6 +125,4 @@ function collectParsersFromLanguages(option, languages, plugins) {
   }
 }
 
-module.exports = {
-  getSupportInfo,
-};
+export { getSupportInfo };
diff --git a/src/standalone.js b/src/standalone.js
index 9f38ffe45..2f809f2a9 100644
--- a/src/standalone.js
+++ b/src/standalone.js
@@ -1,7 +1,7 @@
 import { createRequire } from "module";
 import core from "./main/core.js";
 import { getSupportInfo } from "./main/support.js";
-import sharedUtil from "./common/util-shared.js";
+import * as sharedUtil from "./common/util-shared.js";
 import languages from "./languages.js";
 import doc from "./document/index.js";
 
diff --git a/tests/integration/__tests__/bundle.js b/tests/integration/__tests__/bundle.js
index 57c23a1f7..523f29556 100644
--- a/tests/integration/__tests__/bundle.js
+++ b/tests/integration/__tests__/bundle.js
@@ -2,7 +2,7 @@ import path from "node:path";
 import createEsmUtils from "esm-utils";
 import fastGlob from "fast-glob";
 import { projectRoot } from "../env.js";
-import coreOptions from "../../../src/main/core-options.js";
+import * as coreOptions from "../../../src/main/core-options.js";
 import codeSamples from "../../../website/playground/codeSamples.mjs";
 import jestPathSerializer from "../path-serializer.js";
 
diff --git a/tests/integration/__tests__/util-shared.js b/tests/integration/__tests__/util-shared.js
index 6947373e5..d3d23fe14 100644
--- a/tests/integration/__tests__/util-shared.js
+++ b/tests/integration/__tests__/util-shared.js
@@ -1,4 +1,4 @@
-import sharedUtil from "../../../src/common/util-shared.js";
+import * as sharedUtil from "../../../src/common/util-shared.js";
 
 test("shared util has correct structure", () => {
   expect(typeof sharedUtil.getMaxContinuousCount).toBe("function");