diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index abd521300..9e8b6442a 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -176,8 +176,6 @@ module.exports = {
     {
       files: [
         "**/*.cjs",
-        "src/document/**/*.js",
-        "src/utils/**/*.js",
         "scripts/tools/eslint-plugin-prettier-internal-rules/**/*.js",
         "website/**/*.js",
         "tests/integration/plugins/automatic/prettier-plugin-bar.js",
diff --git a/scripts/build/bundler.mjs b/scripts/build/bundler.mjs
index 93b4a09ed..2b55634b8 100644
--- a/scripts/build/bundler.mjs
+++ b/scripts/build/bundler.mjs
@@ -99,6 +99,8 @@ function* getEsbuildOptions(bundle, buildOptions) {
       "src/language-js/parse/parsers.js",
       "src/language-markdown/parsers.js",
       "src/language-yaml/parsers.js",
+      // This module requires file access, should not include in universal bundle
+      "src/utils/get-interpreter.js",
     ]) {
       replaceModule[path.join(PROJECT_ROOT, file)] =
         EXPORT_UNDEFINED_MODULE_REPLACEMENT;
diff --git a/scripts/build/config.mjs b/scripts/build/config.mjs
index 2bb07e4c1..8a9babe72 100644
--- a/scripts/build/config.mjs
+++ b/scripts/build/config.mjs
@@ -194,6 +194,7 @@ const coreBundles = [
     target: "universal",
     format: "umd",
     minify: false,
+    isEsm: true,
   },
   {
     input: "src/standalone.js",
diff --git a/src/cli/package.json b/src/cli/package.json
deleted file mode 100644
index b4cec2846..000000000
--- a/src/cli/package.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "//TODO": "Remove this file when we close #10157",
-  "type": "module",
-  "description": "A package.json file to use `.js` files in this directory as ES module."
-}
diff --git a/src/common/end-of-line.cjs b/src/common/end-of-line.cjs
deleted file mode 100644
index 0c6365a28..000000000
--- a/src/common/end-of-line.cjs
+++ /dev/null
@@ -1,54 +0,0 @@
-// 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/document/doc-builders.js b/src/document/doc-builders.js
index c119695be..16cc292e2 100644
--- a/src/document/doc-builders.js
+++ b/src/document/doc-builders.js
@@ -1,5 +1,3 @@
-"use strict";
-
 /**
  * TBD properly tagged union for Doc object type is needed here.
  *
@@ -263,7 +261,7 @@ function label(label, contents) {
   return { type: "label", label, contents };
 }
 
-module.exports = {
+export {
   concat,
   join,
   line,
diff --git a/src/document/doc-debug.js b/src/document/doc-debug.js
index 02a65e436..b85f714f8 100644
--- a/src/document/doc-debug.js
+++ b/src/document/doc-debug.js
@@ -1,6 +1,4 @@
-"use strict";
-
-const { isConcat, getDocParts } = require("./doc-utils.js");
+import { isConcat, getDocParts } from "./doc-utils.js";
 
 function flattenDoc(doc) {
   if (!doc) {
@@ -210,4 +208,4 @@ function printDocToDebug(doc) {
   }
 }
 
-module.exports = { printDocToDebug };
+export { printDocToDebug };
diff --git a/src/document/doc-printer.js b/src/document/doc-printer.js
index a8e422178..7cdecf5ab 100644
--- a/src/document/doc-printer.js
+++ b/src/document/doc-printer.js
@@ -1,10 +1,8 @@
-"use strict";
-
-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");
-const { isConcat, getDocParts } = require("./doc-utils.js");
+import { convertEndOfLineToChars } from "../common/end-of-line.js";
+import getLast from "../utils/get-last.js";
+import getStringWidth from "../utils/get-string-width.js";
+import { fill, cursor, indent } from "./doc-builders.js";
+import { isConcat, getDocParts } from "./doc-utils.js";
 
 /** @type {Record<symbol, typeof MODE_BREAK | typeof MODE_FLAT>} */
 let groupModeMap;
@@ -603,4 +601,4 @@ function printDocToString(doc, options) {
   return { formatted: out.join("") };
 }
 
-module.exports = { printDocToString };
+export { printDocToString };
diff --git a/src/document/doc-utils.js b/src/document/doc-utils.js
index 7392976b1..d97e59ef1 100644
--- a/src/document/doc-utils.js
+++ b/src/document/doc-utils.js
@@ -1,7 +1,5 @@
-"use strict";
-
-const getLast = require("../utils/get-last.js");
-const { literalline, join } = require("./doc-builders.js");
+import getLast from "../utils/get-last.js";
+import { literalline, join } from "./doc-builders.js";
 
 const isConcat = (doc) => Array.isArray(doc) || (doc && doc.type === "concat");
 const getDocParts = (doc) => {
@@ -412,7 +410,7 @@ function canBreak(doc) {
   return findInDoc(doc, canBreakFn, false);
 }
 
-module.exports = {
+export {
   isConcat,
   getDocParts,
   willBreak,
diff --git a/src/document/index.js b/src/document/index.js
index 03eebf216..8653e5c64 100644
--- a/src/document/index.js
+++ b/src/document/index.js
@@ -1,12 +1,17 @@
-"use strict";
+import * as builders from "./doc-builders.js";
+import * as printer from "./doc-printer.js";
+import * as utils from "./doc-utils.js";
+import * as debug from "./doc-debug.js";
 
 /**
  * @typedef {import("./doc-builders").Doc} Doc
  */
 
-module.exports = {
-  builders: require("./doc-builders.js"),
-  printer: require("./doc-printer.js"),
-  utils: require("./doc-utils.js"),
-  debug: require("./doc-debug.js"),
+const doc = {
+  builders,
+  printer,
+  utils,
+  debug,
 };
+
+export default doc;
diff --git a/src/document/package.json b/src/document/package.json
deleted file mode 100644
index 54d221724..000000000
--- a/src/document/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/options.js b/src/main/options.js
index 25f213ce4..d118ff94c 100644
--- a/src/main/options.js
+++ b/src/main/options.js
@@ -1,7 +1,7 @@
-import { createRequire } from "module";
 import path from "path";
 import { UndefinedParserError } from "../common/errors.js";
 import { getSupportInfo } from "../main/support.js";
+import getInterpreter from "../utils/get-interpreter.js";
 import { normalizeApiOptions } from "./options-normalizer.js";
 import { resolveParser } from "./parser.js";
 
@@ -139,10 +139,6 @@ 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");
     const interpreter = getInterpreter(filepath);
     language = languages.find(
       (language) =>
diff --git a/src/utils/arrayify.js b/src/utils/arrayify.js
index 6cd24da84..45e776357 100644
--- a/src/utils/arrayify.js
+++ b/src/utils/arrayify.js
@@ -1,7 +1,7 @@
-"use strict";
-
-module.exports = (object, keyName) =>
+const arrayify = (object, keyName) =>
   Object.entries(object).map(([key, value]) => ({
     [keyName]: key,
     ...value,
   }));
+
+export default arrayify;
diff --git a/src/utils/create-language.js b/src/utils/create-language.js
index 37ed075aa..5b384cc15 100644
--- a/src/utils/create-language.js
+++ b/src/utils/create-language.js
@@ -1,10 +1,10 @@
-"use strict";
-
-module.exports = function (linguistData, override) {
+function createLanguage(linguistData, override) {
   const { languageId, ...rest } = linguistData;
   return {
     linguistLanguageId: languageId,
     ...rest,
     ...override(linguistData),
   };
-};
+}
+
+export default createLanguage;
diff --git a/src/utils/front-matter/parse.js b/src/utils/front-matter/parse.js
index 0efc79add..04ba0d38a 100644
--- a/src/utils/front-matter/parse.js
+++ b/src/utils/front-matter/parse.js
@@ -1,5 +1,3 @@
-"use strict";
-
 const frontMatterRegex = new RegExp(
   "^(?<startDelimiter>-{3}|\\+{3})" +
     // trailing spaces after delimiters are allowed
@@ -47,4 +45,4 @@ function parse(text) {
   };
 }
 
-module.exports = parse;
+export default parse;
diff --git a/src/utils/front-matter/print.js b/src/utils/front-matter/print.js
index 5de6ee784..2e69868a4 100644
--- a/src/utils/front-matter/print.js
+++ b/src/utils/front-matter/print.js
@@ -1,8 +1,8 @@
-"use strict";
+import doc from "../../document/index.js";
 
 const {
   builders: { hardline, markAsRoot },
-} = require("../../document/index.js");
+} = doc;
 
 function print(node, textToDoc) {
   if (node.lang === "yaml") {
@@ -20,4 +20,4 @@ function print(node, textToDoc) {
   }
 }
 
-module.exports = print;
+export default print;
diff --git a/src/utils/get-file-content-or-null.js b/src/utils/get-file-content-or-null.js
index 69d3eaef6..67c412c79 100644
--- a/src/utils/get-file-content-or-null.js
+++ b/src/utils/get-file-content-or-null.js
@@ -1,6 +1,4 @@
-"use strict";
-
-const fs = require("fs");
+import fs from "fs";
 const fsAsync = fs.promises;
 
 /**
@@ -35,4 +33,4 @@ function handleError(filename, error) {
   throw new Error(`Unable to read ${filename}: ${error.message}`);
 }
 
-module.exports = getFileContentOrNull;
+export default getFileContentOrNull;
diff --git a/src/utils/get-interpreter.js b/src/utils/get-interpreter.js
index c67fe6324..61a5d71dc 100644
--- a/src/utils/get-interpreter.js
+++ b/src/utils/get-interpreter.js
@@ -1,7 +1,5 @@
-"use strict";
-
-const fs = require("fs");
-const readlines = require("n-readlines");
+import fs from "fs";
+import readlines from "n-readlines";
 
 function getInterpreter(filepath) {
   /* istanbul ignore next */
@@ -49,4 +47,4 @@ function getInterpreter(filepath) {
   }
 }
 
-module.exports = getInterpreter;
+export default getInterpreter;
diff --git a/src/utils/get-last.js b/src/utils/get-last.js
index 371abf867..170e21fe8 100644
--- a/src/utils/get-last.js
+++ b/src/utils/get-last.js
@@ -1,5 +1,3 @@
-"use strict";
-
 const getLast = (arr) => arr[arr.length - 1];
 
-module.exports = getLast;
+export default getLast;
diff --git a/src/utils/get-string-width.js b/src/utils/get-string-width.js
index d96612d3d..864df308a 100644
--- a/src/utils/get-string-width.js
+++ b/src/utils/get-string-width.js
@@ -1,6 +1,4 @@
-"use strict";
-
-const stringWidth = require("../../vendors/string-width.js").default;
+import stringWidth from "string-width";
 
 const notAsciiRegex = /[^\x20-\x7F]/;
 
@@ -21,4 +19,4 @@ function getStringWidth(text) {
   return stringWidth(text);
 }
 
-module.exports = getStringWidth;
+export default getStringWidth;
diff --git a/src/utils/is-non-empty-array.js b/src/utils/is-non-empty-array.js
index 0456053bd..7006cd529 100644
--- a/src/utils/is-non-empty-array.js
+++ b/src/utils/is-non-empty-array.js
@@ -1,5 +1,3 @@
-"use strict";
-
 /**
  * @param {any} object
  * @returns {object is Array<any>}
@@ -8,4 +6,4 @@ function isNonEmptyArray(object) {
   return Array.isArray(object) && object.length > 0;
 }
 
-module.exports = isNonEmptyArray;
+export default isNonEmptyArray;
diff --git a/src/utils/line-column-to-index.js b/src/utils/line-column-to-index.js
index 09911a5b2..7cf626e6d 100644
--- a/src/utils/line-column-to-index.js
+++ b/src/utils/line-column-to-index.js
@@ -1,10 +1,10 @@
-"use strict";
-
 // Super inefficient, needs to be cached.
-module.exports = function (lineColumn, text) {
+function lineColumnToIndex(lineColumn, text) {
   let index = 0;
   for (let i = 0; i < lineColumn.line - 1; ++i) {
     index = text.indexOf("\n", index) + 1;
   }
   return index + lineColumn.column;
-};
+}
+
+export default lineColumnToIndex;
diff --git a/src/utils/load-json5.js b/src/utils/load-json5.js
index 126aaf64c..1232c6560 100644
--- a/src/utils/load-json5.js
+++ b/src/utils/load-json5.js
@@ -1,12 +1,12 @@
-"use strict";
+import json5 from "json5";
 
-const { parse } = require("json5");
-
-module.exports = function (filePath, content) {
+function loadJson5(filePath, content) {
   try {
-    return parse(content);
+    return json5.parse(content);
   } catch (error) {
     error.message = `JSON5 Error in ${filePath}:\n${error.message}`;
     throw error;
   }
-};
+}
+
+export default loadJson5;
diff --git a/src/utils/load-toml.js b/src/utils/load-toml.js
index 59c475456..a3ba1da41 100644
--- a/src/utils/load-toml.js
+++ b/src/utils/load-toml.js
@@ -1,12 +1,12 @@
-"use strict";
+import parse from "@iarna/toml/parse-string.js";
 
-const parse = require("@iarna/toml/parse-string");
-
-module.exports = function (filePath, content) {
+function loadToml(filePath, content) {
   try {
     return parse(content);
   } catch (error) {
     error.message = `TOML Error in ${filePath}:\n${error.message}`;
     throw error;
   }
-};
+}
+
+export default loadToml;
diff --git a/src/utils/package.json b/src/utils/package.json
deleted file mode 100644
index 54d221724..000000000
--- a/src/utils/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/utils/text/get-next-non-space-non-comment-character-index-with-start-index.js b/src/utils/text/get-next-non-space-non-comment-character-index-with-start-index.js
index 237b629a9..5d65fbcb6 100644
--- a/src/utils/text/get-next-non-space-non-comment-character-index-with-start-index.js
+++ b/src/utils/text/get-next-non-space-non-comment-character-index-with-start-index.js
@@ -1,9 +1,7 @@
-"use strict";
-
-const skipInlineComment = require("./skip-inline-comment.js");
-const skipNewline = require("./skip-newline.js");
-const skipTrailingComment = require("./skip-trailing-comment.js");
-const { skipSpaces } = require("./skip.js");
+import skipInlineComment from "./skip-inline-comment.js";
+import skipNewline from "./skip-newline.js";
+import skipTrailingComment from "./skip-trailing-comment.js";
+import { skipSpaces } from "./skip.js";
 
 /**
  * @param {string} text
@@ -25,4 +23,4 @@ function getNextNonSpaceNonCommentCharacterIndexWithStartIndex(text, idx) {
   return nextIdx;
 }
 
-module.exports = getNextNonSpaceNonCommentCharacterIndexWithStartIndex;
+export default getNextNonSpaceNonCommentCharacterIndexWithStartIndex;
diff --git a/src/utils/text/skip-inline-comment.js b/src/utils/text/skip-inline-comment.js
index 1b47494d0..5ee01689b 100644
--- a/src/utils/text/skip-inline-comment.js
+++ b/src/utils/text/skip-inline-comment.js
@@ -1,5 +1,3 @@
-"use strict";
-
 /**
  * @param {string} text
  * @param {number | false} index
@@ -21,4 +19,4 @@ function skipInlineComment(text, index) {
   return index;
 }
 
-module.exports = skipInlineComment;
+export default skipInlineComment;
diff --git a/src/utils/text/skip-newline.js b/src/utils/text/skip-newline.js
index d1d674086..6dfee8108 100644
--- a/src/utils/text/skip-newline.js
+++ b/src/utils/text/skip-newline.js
@@ -1,5 +1,3 @@
-"use strict";
-
 /** @typedef {import("./skip").SkipOptions} SkipOptions */
 
 // This one doesn't use the above helper function because it wants to
@@ -51,4 +49,4 @@ function skipNewline(text, index, opts) {
   return index;
 }
 
-module.exports = skipNewline;
+export default skipNewline;
diff --git a/src/utils/text/skip-trailing-comment.js b/src/utils/text/skip-trailing-comment.js
index 13c74d057..00a711a93 100644
--- a/src/utils/text/skip-trailing-comment.js
+++ b/src/utils/text/skip-trailing-comment.js
@@ -1,6 +1,4 @@
-"use strict";
-
-const { skipEverythingButNewLine } = require("./skip.js");
+import { skipEverythingButNewLine } from "./skip.js";
 
 /**
  * @param {string} text
@@ -19,4 +17,4 @@ function skipTrailingComment(text, index) {
   return index;
 }
 
-module.exports = skipTrailingComment;
+export default skipTrailingComment;
diff --git a/src/utils/text/skip.js b/src/utils/text/skip.js
index 0e37e474e..c5ee42ce7 100644
--- a/src/utils/text/skip.js
+++ b/src/utils/text/skip.js
@@ -1,5 +1,3 @@
-"use strict";
-
 /**
  * @typedef {{backwards?: boolean}} SkipOptions
  */
@@ -62,9 +60,4 @@ const skipToLineEnd = skip(",; \t");
  */
 const skipEverythingButNewLine = skip(/[^\n\r]/);
 
-module.exports = {
-  skipWhitespace,
-  skipSpaces,
-  skipToLineEnd,
-  skipEverythingButNewLine,
-};
+export { skipWhitespace, skipSpaces, skipToLineEnd, skipEverythingButNewLine };
diff --git a/src/utils/try-combinations.js b/src/utils/try-combinations.js
index f7edd9e48..4e9714549 100644
--- a/src/utils/try-combinations.js
+++ b/src/utils/try-combinations.js
@@ -1,5 +1,3 @@
-"use strict";
-
 function tryCombinations(...combinations) {
   let firstError;
   for (const [index, fn] of combinations.entries()) {
@@ -14,4 +12,4 @@ function tryCombinations(...combinations) {
   return { error: firstError };
 }
 
-module.exports = tryCombinations;
+export default tryCombinations;