diff --git a/Herebyfile.mjs b/Herebyfile.mjs
index 8447834a6338a..bd67e520c2351 100644
--- a/Herebyfile.mjs
+++ b/Herebyfile.mjs
@@ -1,6 +1,5 @@
 // @ts-check
 import { CancelToken } from "@esfx/canceltoken";
-import assert from "assert";
 import chalk from "chalk";
 import chokidar from "chokidar";
 import esbuild from "esbuild";
@@ -172,7 +171,6 @@ async function runDtsBundler(entrypoint, output) {
  * @param {BundlerTaskOptions} [taskOptions]
  *
  * @typedef BundlerTaskOptions
- * @property {boolean} [exportIsTsObject]
  * @property {boolean} [treeShaking]
  * @property {boolean} [usePublicAPI]
  * @property {() => void} [onWatchRebuild]
@@ -180,17 +178,15 @@ async function runDtsBundler(entrypoint, output) {
 function createBundler(entrypoint, outfile, taskOptions = {}) {
     const getOptions = memoize(async () => {
         const copyright = await getCopyrightHeader();
-        const banner = taskOptions.exportIsTsObject ? "var ts = {}; ((module) => {" : "";
-
         /** @type {esbuild.BuildOptions} */
         const options = {
             entryPoints: [entrypoint],
-            banner: { js: copyright + banner },
+            banner: { js: copyright },
             bundle: true,
             outfile,
             platform: "node",
             target: ["es2020", "node14.17"],
-            format: "cjs",
+            format: "esm",
             sourcemap: "linked",
             sourcesContent: false,
             treeShaking: taskOptions.treeShaking,
@@ -200,66 +196,17 @@ function createBundler(entrypoint, outfile, taskOptions = {}) {
         };
 
         if (taskOptions.usePublicAPI) {
-            options.external = ["./typescript.js"];
             options.plugins = options.plugins || [];
             options.plugins.push({
-                name: "remap-typescript-to-require",
+                name: "remap-typescript-to-public-api",
                 setup(build) {
-                    build.onLoad({ filter: /src[\\/]typescript[\\/]typescript\.ts$/ }, () => {
-                        return { contents: `export * from "./typescript.js"` };
+                    build.onResolve({ filter: /^(?:\.\.[\\/])*typescript[\\/]typescript\.js$/ }, () => {
+                        return { path: "./typescript.js", external: true };
                     });
                 },
             });
         }
 
-        if (taskOptions.exportIsTsObject) {
-            // Monaco bundles us as ESM by wrapping our code with something that defines module.exports
-            // but then does not use it, instead using the `ts` variable. Ensure that if we think we're CJS
-            // that we still set `ts` to the module.exports object.
-            options.footer = { js: `})(typeof module !== "undefined" && module.exports ? module : { exports: ts });\nif (typeof module !== "undefined" && module.exports) { ts = module.exports; }` };
-
-            // esbuild converts calls to "require" to "__require"; this function
-            // calls the real require if it exists, or throws if it does not (rather than
-            // throwing an error like "require not defined"). But, since we want typescript
-            // to be consumable by other bundlers, we need to convert these calls back to
-            // require so our imports are visible again.
-            //
-            // To fix this, we redefine "require" to a name we're unlikely to use with the
-            // same length as "require", then replace it back to "require" after bundling,
-            // ensuring that source maps still work.
-            //
-            // See: https://github.com/evanw/esbuild/issues/1905
-            const require = "require";
-            const fakeName = "Q".repeat(require.length);
-            const fakeNameRegExp = new RegExp(fakeName, "g");
-            options.define = { [require]: fakeName };
-
-            // For historical reasons, TypeScript does not set __esModule. Hack esbuild's __toCommonJS to be a noop.
-            // We reference `__copyProps` to ensure the final bundle doesn't have any unreferenced code.
-            const toCommonJsRegExp = /var __toCommonJS .*/;
-            const toCommonJsRegExpReplacement = "var __toCommonJS = (mod) => (__copyProps, mod); // Modified helper to skip setting __esModule.";
-
-            options.plugins = options.plugins || [];
-            options.plugins.push(
-                {
-                    name: "post-process",
-                    setup: build => {
-                        build.onEnd(async () => {
-                            let contents = await fs.promises.readFile(outfile, "utf-8");
-                            contents = contents.replace(fakeNameRegExp, require);
-                            let matches = 0;
-                            contents = contents.replace(toCommonJsRegExp, () => {
-                                matches++;
-                                return toCommonJsRegExpReplacement;
-                            });
-                            assert(matches === 1, "Expected exactly one match for __toCommonJS");
-                            await fs.promises.writeFile(outfile, contents);
-                        });
-                    },
-                },
-            );
-        }
-
         return options;
     });
 
@@ -304,6 +251,7 @@ let printedWatchWarning = false;
  * @param {string} options.builtEntrypoint
  * @param {string} options.output
  * @param {Task[]} [options.mainDeps]
+ * @param {boolean} [options.reexportDefault]
  * @param {BundlerTaskOptions} [options.bundlerOptions]
  */
 function entrypointBuildTask(options) {
@@ -324,13 +272,13 @@ function entrypointBuildTask(options) {
     });
 
     /**
-     * Writes a CJS module that reexports another CJS file. E.g. given
+     * Writes a module that reexports another file. E.g. given
      * `options.builtEntrypoint = "./built/local/tsc/tsc.js"` and
      * `options.output = "./built/local/tsc.js"`, this will create a file
      * named "./built/local/tsc.js" containing:
      *
      * ```
-     * module.exports = require("./tsc/tsc.js")
+     * export * from "./tsc/tsc.js";
      * ```
      */
     const shim = task({
@@ -338,8 +286,19 @@ function entrypointBuildTask(options) {
         run: async () => {
             const outDir = path.dirname(options.output);
             await fs.promises.mkdir(outDir, { recursive: true });
-            const moduleSpecifier = path.relative(outDir, options.builtEntrypoint);
-            await fs.promises.writeFile(options.output, `module.exports = require("./${moduleSpecifier.replace(/[\\/]/g, "/")}")`);
+            const moduleSpecifier = path.relative(outDir, options.builtEntrypoint).replace(/[\\/]/g, "/");
+            const lines = [
+                `export * from "./${moduleSpecifier}";`,
+            ];
+
+            if (options.reexportDefault) {
+                lines.push(
+                    `import _default from "./${moduleSpecifier}";`,
+                    `export default _default;`,
+                );
+            }
+
+            await fs.promises.writeFile(options.output, lines.join("\n") + "\n");
         },
     });
 
@@ -404,7 +363,7 @@ const { main: services, build: buildServices, watch: watchServices } = entrypoin
     builtEntrypoint: "./built/local/typescript/typescript.js",
     output: "./built/local/typescript.js",
     mainDeps: [generateLibs],
-    bundlerOptions: { exportIsTsObject: true },
+    reexportDefault: true,
 });
 export { services, watchServices };
 
@@ -445,25 +404,22 @@ export const watchMin = task({
     dependencies: [watchTsc, watchTsserver],
 });
 
-// This is technically not enough to make tsserverlibrary loadable in the
-// browser, but it's unlikely that anyone has actually been doing that.
 const lsslJs = `
-if (typeof module !== "undefined" && module.exports) {
-    module.exports = require("./typescript.js");
-}
-else {
-    throw new Error("tsserverlibrary requires CommonJS; use typescript.js instead");
-}
+import ts from "./typescript.js";
+export * from "./typescript.js";
+export default ts;
 `;
 
 const lsslDts = `
-import ts = require("./typescript.js");
-export = ts;
+import ts from "./typescript.js";
+export * from "./typescript.js";
+export default ts;
 `;
 
 const lsslDtsInternal = `
-import ts = require("./typescript.internal.js");
-export = ts;
+import ts from "./typescript.internal.js";
+export * from "./typescript.internal.js";
+export default ts;
 `;
 
 /**
@@ -504,7 +460,7 @@ const { main: tests, watch: watchTests } = entrypointBuildTask({
     description: "Builds the test infrastructure",
     buildDeps: [generateDiagnostics],
     project: "src/testRunner",
-    srcEntrypoint: "./src/testRunner/_namespaces/Harness.ts",
+    srcEntrypoint: "./src/testRunner/runner.ts",
     builtEntrypoint: "./built/local/testRunner/runner.js",
     output: testRunner,
     mainDeps: [generateLibs],
diff --git a/bin/tsc b/bin/tsc
index 19c62bf7a0004..bef1027ea20a1 100755
--- a/bin/tsc
+++ b/bin/tsc
@@ -1,2 +1,2 @@
 #!/usr/bin/env node
-require('../lib/tsc.js')
+import '../lib/tsc.js';
diff --git a/bin/tsserver b/bin/tsserver
index 7143b6a73ab8a..d90c1a2ece3ff 100755
--- a/bin/tsserver
+++ b/bin/tsserver
@@ -1,2 +1,2 @@
 #!/usr/bin/env node
-require('../lib/tsserver.js')
+import '../lib/tsserver.js';
diff --git a/package-lock.json b/package-lock.json
index 2c467651009a9..130c0800768d4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16,6 +16,7 @@
                 "@esfx/canceltoken": "^1.0.0",
                 "@octokit/rest": "^20.1.1",
                 "@types/chai": "^4.3.16",
+                "@types/diff": "^5.2.1",
                 "@types/microsoft__typescript-etw": "^0.1.3",
                 "@types/minimist": "^1.2.5",
                 "@types/mocha": "^10.0.6",
@@ -976,6 +977,12 @@
             "integrity": "sha512-PatH4iOdyh3MyWtmHVFXLWCCIhUbopaltqddG9BzB+gMIzee2MJrvd+jouii9Z3wzQJruGWAm7WOMjgfG8hQlQ==",
             "dev": true
         },
+        "node_modules/@types/diff": {
+            "version": "5.2.1",
+            "resolved": "https://registry.npmjs.org/@types/diff/-/diff-5.2.1.tgz",
+            "integrity": "sha512-uxpcuwWJGhe2AR1g8hD9F5OYGCqjqWnBUQFD8gMZsDbv8oPHzxJF6iMO6n8Tk0AdzlxoaaoQhOYlIg/PukVU8g==",
+            "dev": true
+        },
         "node_modules/@types/istanbul-lib-coverage": {
             "version": "2.0.6",
             "resolved": "https://registry.npmjs.org/@types/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.6.tgz",
@@ -5011,6 +5018,12 @@
             "integrity": "sha512-PatH4iOdyh3MyWtmHVFXLWCCIhUbopaltqddG9BzB+gMIzee2MJrvd+jouii9Z3wzQJruGWAm7WOMjgfG8hQlQ==",
             "dev": true
         },
+        "@types/diff": {
+            "version": "5.2.1",
+            "resolved": "https://registry.npmjs.org/@types/diff/-/diff-5.2.1.tgz",
+            "integrity": "sha512-uxpcuwWJGhe2AR1g8hD9F5OYGCqjqWnBUQFD8gMZsDbv8oPHzxJF6iMO6n8Tk0AdzlxoaaoQhOYlIg/PukVU8g==",
+            "dev": true
+        },
         "@types/istanbul-lib-coverage": {
             "version": "2.0.6",
             "resolved": "https://registry.npmjs.org/@types/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.6.tgz",
diff --git a/package.json b/package.json
index 4b300c1a0d6c5..a7389f387e60a 100644
--- a/package.json
+++ b/package.json
@@ -43,6 +43,7 @@
         "@esfx/canceltoken": "^1.0.0",
         "@octokit/rest": "^20.1.1",
         "@types/chai": "^4.3.16",
+        "@types/diff": "^5.2.1",
         "@types/microsoft__typescript-etw": "^0.1.3",
         "@types/minimist": "^1.2.5",
         "@types/mocha": "^10.0.6",
diff --git a/patchProcessGetBuiltin.cjs b/patchProcessGetBuiltin.cjs
new file mode 100644
index 0000000000000..f147fca8b3cb6
--- /dev/null
+++ b/patchProcessGetBuiltin.cjs
@@ -0,0 +1,9 @@
+const _module = require("module");
+
+/** @type {(name: string) => any} */
+function getBuiltinModule(name) {
+    if (!_module.isBuiltin(name)) return undefined;
+    return require(name);
+}
+
+process.getBuiltinModule = getBuiltinModule;
diff --git a/scripts/browserIntegrationTest.mjs b/scripts/browserIntegrationTest.mjs
index f1fab43f2213c..f67f84105bcc1 100644
--- a/scripts/browserIntegrationTest.mjs
+++ b/scripts/browserIntegrationTest.mjs
@@ -28,7 +28,7 @@ for (const browserType of browsers) {
 
     await page.setContent(`
     <html>
-    <script>${readFileSync(join("built", "local", "typescript.js"), "utf8")}</script>
+    <script type="module">${readFileSync(join("built", "local", "typescript.js"), "utf8")}</script>
     </html>
     `);
 
diff --git a/scripts/checkModuleFormat.mjs b/scripts/checkModuleFormat.mjs
index ed33b5fb00382..d6ab73eaf624a 100644
--- a/scripts/checkModuleFormat.mjs
+++ b/scripts/checkModuleFormat.mjs
@@ -19,7 +19,7 @@ console.log(`Testing ${typescript}...`);
 /** @type {[fn: (() => Promise<any>), shouldSucceed: boolean][]} */
 const fns = [
     [() => require(typescript).version, true],
-    [() => require(typescript).default.version, false],
+    [() => require(typescript).default.version, true],
     [() => __importDefault(require(typescript)).version, false],
     [() => __importDefault(require(typescript)).default.version, true],
     [() => __importStar(require(typescript)).version, true],
diff --git a/scripts/dtsBundler.mjs b/scripts/dtsBundler.mjs
index e7ace12303e1d..b14e39992cd0d 100644
--- a/scripts/dtsBundler.mjs
+++ b/scripts/dtsBundler.mjs
@@ -357,6 +357,8 @@ function isSelfReference(reference, symbol) {
  * @param {ts.Symbol} moduleSymbol
  */
 function emitAsNamespace(name, parent, moduleSymbol, needExportModifier) {
+    if (name === "default") return;
+
     assert(moduleSymbol.flags & ts.SymbolFlags.ValueModule, "moduleSymbol is not a module");
 
     const fullName = parent ? `${parent}.${name}` : name;
@@ -465,6 +467,7 @@ function emitAsNamespace(name, parent, moduleSymbol, needExportModifier) {
 
 emitAsNamespace("ts", "", moduleSymbol, /*needExportModifier*/ false);
 
+// TODO(jakebailey): require(ESM) - fix this
 write("export = ts;", WriteTarget.Both);
 
 const copyrightNotice = fs.readFileSync(path.join(__dirname, "CopyrightNotice.txt"), "utf-8");
diff --git a/src/.eslintrc.json b/src/.eslintrc.json
index 697574c6a8ec5..3684d3c6fc87a 100644
--- a/src/.eslintrc.json
+++ b/src/.eslintrc.json
@@ -14,7 +14,10 @@
             { "name": "clearInterval" },
             { "name": "setImmediate" },
             { "name": "clearImmediate" },
-            { "name": "performance" }
+            { "name": "performance" },
+            { "name": "require" },
+            { "name": "__dirname" },
+            { "name": "__filename" }
         ]
     },
     "overrides": [
diff --git a/src/cancellationToken/cancellationToken.ts b/src/cancellationToken/cancellationToken.ts
index 4676e9b14e0a3..97c5c7f0612fd 100644
--- a/src/cancellationToken/cancellationToken.ts
+++ b/src/cancellationToken/cancellationToken.ts
@@ -17,7 +17,7 @@ function pipeExists(name: string): boolean {
     return fs.existsSync(name);
 }
 
-function createCancellationToken(args: string[]): ServerCancellationToken {
+export function createCancellationToken(args: string[]): ServerCancellationToken {
     let cancellationPipeName: string | undefined;
     for (let i = 0; i < args.length - 1; i++) {
         if (args[i] === "--cancellationPipeName") {
@@ -66,4 +66,3 @@ function createCancellationToken(args: string[]): ServerCancellationToken {
         };
     }
 }
-export = createCancellationToken;
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index d7f6fe0580d5f..a9005487dd901 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -2730,5 +2730,5 @@ export function isNodeLikeSystem(): boolean {
     return typeof process !== "undefined"
         && !!process.nextTick
         && !(process as any).browser
-        && typeof require !== "undefined";
+        && typeof (process as any).getBuiltinModule === "function";
 }
diff --git a/src/compiler/nodeGetBuiltinModule.ts b/src/compiler/nodeGetBuiltinModule.ts
new file mode 100644
index 0000000000000..e8c26c8df53e8
--- /dev/null
+++ b/src/compiler/nodeGetBuiltinModule.ts
@@ -0,0 +1,12 @@
+export function nodeCreateRequire(path: string): NodeJS.Require {
+    const mod = nodeGetBuiltinModule("module") as typeof import("module") | undefined;
+    if (!mod) throw new Error("missing node:module");
+    return mod.createRequire(path);
+}
+
+function nodeGetBuiltinModule(moduleName: string): unknown {
+    if (typeof process === "undefined" || typeof (process as any).getBuiltinModule !== "function") {
+        throw new Error("process.getBuiltinModule is not supported in this environment.");
+    }
+    return (process as any).getBuiltinModule(moduleName);
+}
diff --git a/src/compiler/perfLogger.ts b/src/compiler/perfLogger.ts
index f2476db967541..f02e8eb2c366c 100644
--- a/src/compiler/perfLogger.ts
+++ b/src/compiler/perfLogger.ts
@@ -1,3 +1,5 @@
+import { nodeCreateRequire } from "./nodeGetBuiltinModule.js";
+
 /** @internal */
 export interface PerfLogger {
     logEvent(msg: string): void;
@@ -27,6 +29,7 @@ export interface PerfLogger {
 let etwModule: typeof import("@microsoft/typescript-etw") | undefined;
 try {
     const etwModulePath = process.env.TS_ETW_MODULE_PATH ?? "./node_modules/@microsoft/typescript-etw";
+    const require = nodeCreateRequire(import.meta.url);
 
     // require() will throw an exception if the module is not found
     // It may also return undefined if not installed properly
diff --git a/src/compiler/performanceCore.ts b/src/compiler/performanceCore.ts
index abff50eb8aae6..4086e39116ef1 100644
--- a/src/compiler/performanceCore.ts
+++ b/src/compiler/performanceCore.ts
@@ -1,4 +1,5 @@
 import { isNodeLikeSystem } from "./_namespaces/ts.js";
+import { nodeCreateRequire } from "./nodeGetBuiltinModule.js";
 
 // The following definitions provide the minimum compatible support for the Web Performance User Timings API
 // between browsers and NodeJS:
@@ -31,7 +32,8 @@ function tryGetPerformance() {
     if (isNodeLikeSystem()) {
         try {
             // By default, only write native events when generating a cpu profile or using the v8 profiler.
-            const { performance } = require("perf_hooks") as typeof import("perf_hooks");
+            const require = nodeCreateRequire(import.meta.url);
+            const { performance } = require("perf_hooks");
             return {
                 shouldWriteNativeEvents: false,
                 performance,
diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index a8fdd4d156822..66aa231b71e92 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -47,6 +47,7 @@ import {
     WatchOptions,
     writeFileEnsuringDirectories,
 } from "./_namespaces/ts.js";
+import { nodeCreateRequire } from "./nodeGetBuiltinModule.js";
 
 declare function setTimeout(handler: (...args: any[]) => void, timeout: number): any;
 declare function clearTimeout(handle: any): void;
@@ -1466,9 +1467,15 @@ export let sys: System = (() => {
     const byteOrderMarkIndicator = "\uFEFF";
 
     function getNodeSystem(): System {
+        // TODO(jakebailey): Only use createRequire for sys.require.
+        const require = nodeCreateRequire(import.meta.url);
+        const _path: typeof import("path") = require("path");
+        const _url: typeof import("url") = require("url");
+        const __filename = _url.fileURLToPath(new URL(import.meta.url));
+        const __dirname = _path.dirname(__filename);
+
         const nativePattern = /^native |^\([^)]+\)$|^(internal[\\/]|[a-zA-Z0-9_\s]+(\.js)?$)/;
         const _fs: typeof import("fs") = require("fs");
-        const _path: typeof import("path") = require("path");
         const _os = require("os");
         // crypto can be absent on reduced node installations
         let _crypto: typeof import("crypto") | undefined;
diff --git a/src/compiler/tracing.ts b/src/compiler/tracing.ts
index 94e9bd57c83b6..985ac39753775 100644
--- a/src/compiler/tracing.ts
+++ b/src/compiler/tracing.ts
@@ -22,6 +22,7 @@ import {
     UnionType,
 } from "./_namespaces/ts.js";
 import * as performance from "./_namespaces/ts.performance.js";
+import { nodeCreateRequire } from "./nodeGetBuiltinModule.js";
 
 /* Tracing events for the compiler. */
 
@@ -60,6 +61,7 @@ export namespace tracingEnabled {
 
         if (fs === undefined) {
             try {
+                const require = nodeCreateRequire(import.meta.url);
                 fs = require("fs");
             }
             catch (e) {
diff --git a/src/harness/findUpDir.ts b/src/harness/findUpDir.ts
index 20b1afe414ece..29008b44726be 100644
--- a/src/harness/findUpDir.ts
+++ b/src/harness/findUpDir.ts
@@ -4,10 +4,14 @@ import {
     join,
     resolve,
 } from "path";
+import { fileURLToPath } from "url";
 
 // search directories upward to avoid hard-wired paths based on the
 // build tree (same as scripts/build/findUpDir.js)
 
+const __filename = fileURLToPath(new URL(import.meta.url));
+const __dirname = dirname(__filename);
+
 export function findUpFile(name: string): string {
     let dir = __dirname;
     while (true) {
diff --git a/src/harness/fourslashImpl.ts b/src/harness/fourslashImpl.ts
index 6c7a14535d2c5..2f9a3125dd52f 100644
--- a/src/harness/fourslashImpl.ts
+++ b/src/harness/fourslashImpl.ts
@@ -1,3 +1,4 @@
+import sourceMapSupport from "source-map-support";
 import * as fakes from "./_namespaces/fakes.js";
 import * as FourSlashInterface from "./_namespaces/FourSlashInterface.js";
 import * as Harness from "./_namespaces/Harness.js";
@@ -4582,22 +4583,9 @@ function runCode(code: string, state: TestState, fileName: string): void {
     const generatedFile = ts.changeExtension(fileName, ".js");
     const wrappedCode = `(function(ts, test, goTo, config, verify, edit, debug, format, cancellation, classification, completion, verifyOperationIsCancelled, ignoreInterpolations) {${code}\n//# sourceURL=${ts.getBaseFileName(generatedFile)}\n})`;
 
-    type SourceMapSupportModule = typeof import("source-map-support") & {
-        // TODO(rbuckton): This is missing from the DT definitions and needs to be added.
-        resetRetrieveHandlers(): void;
-    };
-
     // Provide the content of the current test to 'source-map-support' so that it can give us the correct source positions
     // for test failures.
-    let sourceMapSupportModule: SourceMapSupportModule | undefined;
-    try {
-        sourceMapSupportModule = require("source-map-support");
-    }
-    catch {
-        // do nothing
-    }
-
-    sourceMapSupportModule?.install({
+    sourceMapSupport?.install({
         retrieveFile: path => {
             return path === generatedFile ? wrappedCode :
                 undefined!;
@@ -4623,7 +4611,7 @@ function runCode(code: string, state: TestState, fileName: string): void {
         throw err;
     }
     finally {
-        sourceMapSupportModule?.resetRetrieveHandlers();
+        sourceMapSupport?.resetRetrieveHandlers();
     }
 }
 
diff --git a/src/harness/harnessIO.ts b/src/harness/harnessIO.ts
index fb0a80b71d457..4c00f974c79d7 100644
--- a/src/harness/harnessIO.ts
+++ b/src/harness/harnessIO.ts
@@ -1,3 +1,6 @@
+import * as Diff from "diff";
+import fs from "fs";
+import pathModule from "path";
 import * as compiler from "./_namespaces/compiler.js";
 import * as documents from "./_namespaces/documents.js";
 import * as fakes from "./_namespaces/fakes.js";
@@ -54,14 +57,6 @@ export const virtualFileSystemRoot = "/";
 
 function createNodeIO(): IO {
     const workspaceRoot = Utils.findUpRoot();
-    let fs: any, pathModule: any;
-    if (require) {
-        fs = require("fs");
-        pathModule = require("path");
-    }
-    else {
-        fs = pathModule = {};
-    }
 
     function deleteFile(path: string) {
         try {
@@ -1018,7 +1013,6 @@ export namespace Compiler {
                 }
                 else if (original.text !== doc.text) {
                     jsCode += `\r\n\r\n!!!! File ${Utils.removeTestPathPrefixes(doc.file)} differs from original emit in noCheck emit\r\n`;
-                    const Diff = require("diff");
                     const expected = original.text;
                     const actual = doc.text;
                     const patch = Diff.createTwoFilesPatch("Expected", "Actual", expected, actual, "The full check baseline", "with noCheck set");
@@ -1514,8 +1508,7 @@ export namespace Baseline {
                 IO.writeFile(actualFileName, encodedActual);
             }
             const errorMessage = getBaselineFileChangedErrorMessage(relativeFileName);
-            if (!!require && opts && opts.PrintDiff) {
-                const Diff = require("diff");
+            if (opts && opts.PrintDiff) {
                 const patch = Diff.createTwoFilesPatch("Expected", "Actual", expected, actual, "The current baseline", "The new version");
                 throw new Error(`${errorMessage}${ts.ForegroundColorEscapeSequences.Grey}\n\n${patch}`);
             }
diff --git a/src/harness/harnessUtils.ts b/src/harness/harnessUtils.ts
index d7989da8d6980..b049c51d5f416 100644
--- a/src/harness/harnessUtils.ts
+++ b/src/harness/harnessUtils.ts
@@ -1,3 +1,4 @@
+import vm from "vm";
 import * as Harness from "./_namespaces/Harness.js";
 import * as ts from "./_namespaces/ts.js";
 
@@ -6,7 +7,6 @@ export function encodeString(s: string): string {
 }
 
 export function evalFile(fileContents: string, fileName: string, nodeContext?: any) {
-    const vm = require("vm");
     if (nodeContext) {
         vm.runInNewContext(fileContents, nodeContext, fileName);
     }
diff --git a/src/testRunner/parallel/host.ts b/src/testRunner/parallel/host.ts
index cbfc9b391c491..f6b1159b969c9 100644
--- a/src/testRunner/parallel/host.ts
+++ b/src/testRunner/parallel/host.ts
@@ -1,3 +1,11 @@
+import { fork } from "child_process";
+import { statSync } from "fs";
+import Mocha from "mocha";
+import ms from "ms";
+import os from "os";
+import path from "path";
+import readline from "readline";
+import tty from "tty";
 import {
     configOption,
     globalTimeout,
@@ -25,21 +33,16 @@ import {
 import * as ts from "../_namespaces/ts.js";
 import * as Utils from "../_namespaces/Utils.js";
 
+import { createRequire } from "module";
+const require = createRequire(import.meta.url);
+
 export function start(importTests: () => Promise<unknown>) {
-    const Mocha = require("mocha") as typeof import("mocha");
     const Base = Mocha.reporters.Base;
     const color = Base.color;
     const cursor = Base.cursor;
-    const ms = require("ms") as typeof import("ms");
-    const readline = require("readline") as typeof import("readline");
-    const os = require("os") as typeof import("os");
-    const tty = require("tty") as typeof import("tty");
     const isatty = tty.isatty(1) && tty.isatty(2);
-    const path = require("path") as typeof import("path");
-    const { fork } = require("child_process") as typeof import("child_process");
-    const { statSync } = require("fs") as typeof import("fs");
 
-    // NOTE: paths for module and types for FailedTestReporter _do not_ line up due to our use of --outFile for run.js
+    // NOTE: paths for module and types for FailedTestReporter _do not_ line up when bundled
     const FailedTestReporter = require(Utils.findUpFile("scripts/failed-tests.cjs")) as typeof import("../../../scripts/failed-tests.cjs");
 
     const perfdataFileNameFragment = ".parallelperf";
diff --git a/src/testRunner/parallel/worker.ts b/src/testRunner/parallel/worker.ts
index 4b61633e45a53..23c089ef35411 100644
--- a/src/testRunner/parallel/worker.ts
+++ b/src/testRunner/parallel/worker.ts
@@ -1,3 +1,4 @@
+import Mocha from "mocha";
 import {
     createRunner,
     globalTimeout,
@@ -39,9 +40,6 @@ export function start(importTests: () => Promise<unknown>) {
     let exceptionsHooked = false;
     hookUncaughtExceptions();
 
-    // Capitalization is aligned with the global `Mocha` namespace for typespace/namespace references.
-    const Mocha = require("mocha") as typeof import("mocha");
-
     /**
      * Mixin helper.
      * @param base The base class constructor.
diff --git a/src/testRunner/unittests/skipJSDocParsing.ts b/src/testRunner/unittests/skipJSDocParsing.ts
index 4fd6e87819628..45c4e67881e8c 100644
--- a/src/testRunner/unittests/skipJSDocParsing.ts
+++ b/src/testRunner/unittests/skipJSDocParsing.ts
@@ -1,10 +1,9 @@
+import * as Diff from "diff";
 import * as Harness from "../_namespaces/Harness.js";
 import * as ts from "../_namespaces/ts.js";
 import * as Utils from "../_namespaces/Utils.js";
 
 describe("unittests:: skipJSDocParsing", () => {
-    const Diff = require("diff");
-
     const kinds = [
         ts.JSDocParsingMode.ParseAll,
         ts.JSDocParsingMode.ParseForTypeErrors,
diff --git a/src/tsserver/nodeServer.ts b/src/tsserver/nodeServer.ts
index 280b0d3b630df..a3429a3ebe7a4 100644
--- a/src/tsserver/nodeServer.ts
+++ b/src/tsserver/nodeServer.ts
@@ -1,3 +1,9 @@
+import childProcess from "child_process";
+import fs from "fs";
+import net from "net";
+import os from "os";
+import readline from "readline";
+import { nodeCreateRequire } from "../compiler/nodeGetBuiltinModule.js";
 import {
     CharacterCodes,
     combinePaths,
@@ -9,7 +15,6 @@ import {
     getDirectoryPath,
     getRootLength,
     LanguageServiceMode,
-    MapLike,
     noop,
     noopFileWatcher,
     normalizePath,
@@ -38,24 +43,6 @@ interface LogOptions {
     logToFile?: boolean;
 }
 
-interface NodeChildProcess {
-    send(message: any, sendHandle?: any): void;
-    on(message: "message" | "exit", f: (m: any) => void): void;
-    kill(): void;
-    pid: number;
-}
-
-interface ReadLineOptions {
-    input: NodeJS.ReadableStream;
-    output?: NodeJS.WritableStream;
-    terminal?: boolean;
-    historySize?: number;
-}
-
-interface NodeSocket {
-    write(data: string, encoding: string): boolean;
-}
-
 function parseLoggingEnvironmentString(logEnvStr: string | undefined): LogOptions {
     if (!logEnvStr) {
         return {};
@@ -124,41 +111,6 @@ function parseServerMode(): LanguageServiceMode | string | undefined {
 /** @internal */
 export function initializeNodeSystem(): StartInput {
     const sys = Debug.checkDefined(ts.sys) as ts.server.ServerHost;
-    const childProcess: {
-        execFileSync(file: string, args: string[], options: { stdio: "ignore"; env: MapLike<string>; }): string | Buffer;
-    } = require("child_process");
-
-    interface Stats {
-        isFile(): boolean;
-        isDirectory(): boolean;
-        isBlockDevice(): boolean;
-        isCharacterDevice(): boolean;
-        isSymbolicLink(): boolean;
-        isFIFO(): boolean;
-        isSocket(): boolean;
-        dev: number;
-        ino: number;
-        mode: number;
-        nlink: number;
-        uid: number;
-        gid: number;
-        rdev: number;
-        size: number;
-        blksize: number;
-        blocks: number;
-        atime: Date;
-        mtime: Date;
-        ctime: Date;
-        birthtime: Date;
-    }
-
-    const fs: {
-        openSync(path: string, options: string): number;
-        close(fd: number, callback: (err: NodeJS.ErrnoException) => void): void;
-        writeSync(fd: number, buffer: Buffer, offset: number, length: number, position?: number): number;
-        statSync(path: string): Stats;
-        stat(path: string, callback?: (err: NodeJS.ErrnoException, stats: Stats) => any): void;
-    } = require("fs");
 
     class Logger implements Logger {
         private seq = 0;
@@ -244,7 +196,7 @@ export function initializeNodeSystem(): StartInput {
             if (this.fd >= 0) {
                 const buf = Buffer.from(s);
                 // eslint-disable-next-line no-restricted-syntax
-                fs.writeSync(this.fd, buf, 0, buf.length, /*position*/ null!); // TODO: GH#18217
+                fs.writeSync(this.fd, buf, 0, buf.length, /*position*/ null); // TODO: GH#18217
             }
             if (this.traceToConsole) {
                 console.warn(s);
@@ -339,8 +291,9 @@ export function initializeNodeSystem(): StartInput {
 
     let cancellationToken: ts.server.ServerCancellationToken;
     try {
-        const factory = require("./cancellationToken");
-        cancellationToken = factory(sys.args);
+        const require = nodeCreateRequire(import.meta.url);
+        const { createCancellationToken } = require("./cancellationToken.js");
+        cancellationToken = createCancellationToken(sys.args);
     }
     catch (e) {
         cancellationToken = ts.server.nullCancellationToken;
@@ -452,23 +405,6 @@ function parseEventPort(eventPortStr: string | undefined) {
     return eventPort !== undefined && !isNaN(eventPort) ? eventPort : undefined;
 }
 function startNodeSession(options: StartSessionOptions, logger: ts.server.Logger, cancellationToken: ts.server.ServerCancellationToken) {
-    const childProcess: {
-        fork(modulePath: string, args: string[], options?: { execArgv: string[]; env?: MapLike<string>; }): NodeChildProcess;
-    } = require("child_process");
-
-    const os: {
-        homedir?(): string;
-        tmpdir(): string;
-    } = require("os");
-
-    const net: {
-        connect(options: { port: number; }, onConnect?: () => void): NodeSocket;
-    } = require("net");
-
-    const readline: {
-        createInterface(options: ReadLineOptions): NodeJS.EventEmitter;
-    } = require("readline");
-
     const rl = readline.createInterface({
         input: process.stdin,
         output: process.stdout,
@@ -476,7 +412,7 @@ function startNodeSession(options: StartSessionOptions, logger: ts.server.Logger
     });
 
     class NodeTypingsInstallerAdapter extends ts.server.TypingsInstallerAdapter {
-        protected override installer!: NodeChildProcess;
+        protected override installer!: childProcess.ChildProcess;
         // This number is essentially arbitrary.  Processing more than one typings request
         // at a time makes sense, but having too many in the pipe results in a hang
         // (see https://github.com/nodejs/node/issues/7657).
@@ -546,7 +482,7 @@ function startNodeSession(options: StartSessionOptions, logger: ts.server.Logger
 
             const typingsInstaller = combinePaths(getDirectoryPath(sys.getExecutingFilePath()), "typingsInstaller.js");
             this.installer = childProcess.fork(typingsInstaller, args, { execArgv });
-            this.installer.on("message", m => this.handleMessage(m));
+            this.installer.on("message", m => this.handleMessage(m as any));
 
             // We have to schedule this event to the next tick
             // cause this fn will be called during
@@ -563,7 +499,7 @@ function startNodeSession(options: StartSessionOptions, logger: ts.server.Logger
 
     class IOSession extends ts.server.Session {
         private eventPort: number | undefined;
-        private eventSocket: NodeSocket | undefined;
+        private eventSocket: net.Socket | undefined;
         private socketEventQueue: { body: any; eventName: string; }[] | undefined;
         /** No longer needed if syntax target is es6 or above. Any access to "this" before initialized will be a runtime error. */
         private constructed: boolean | undefined;
diff --git a/src/tsserver/server.ts b/src/tsserver/server.ts
index dac80d8496f2f..d74ca4f04d645 100644
--- a/src/tsserver/server.ts
+++ b/src/tsserver/server.ts
@@ -1,3 +1,4 @@
+import os from "os";
 import * as ts from "../typescript/typescript.js";
 import { StartInput } from "./common.js";
 import { initializeNodeSystem } from "./nodeServer.js";
@@ -53,4 +54,4 @@ function start({ args, logger, cancellationToken, serverMode, unknownServerMode,
 }
 
 ts.setStackTraceLimit();
-start(initializeNodeSystem(), require("os").platform());
+start(initializeNodeSystem(), os.platform());
diff --git a/src/typescript/typescript.ts b/src/typescript/typescript.ts
index 9e54bbe9c15b0..fa83f781938b1 100644
--- a/src/typescript/typescript.ts
+++ b/src/typescript/typescript.ts
@@ -23,3 +23,5 @@ if (typeof console !== "undefined") {
 }
 
 export * from "./_namespaces/ts.js";
+import * as ts from "./_namespaces/ts.js";
+export default ts;
diff --git a/src/typingsInstaller/nodeTypingsInstaller.ts b/src/typingsInstaller/nodeTypingsInstaller.ts
index 836b64473cb05..984d7b80c5b7e 100644
--- a/src/typingsInstaller/nodeTypingsInstaller.ts
+++ b/src/typingsInstaller/nodeTypingsInstaller.ts
@@ -1,3 +1,4 @@
+import { execFileSync } from "child_process";
 import * as fs from "fs";
 import * as path from "path";
 
@@ -79,10 +80,8 @@ interface ExecSyncOptions {
     cwd: string;
     encoding: "utf-8";
 }
-type ExecSync = (command: string, options: ExecSyncOptions) => string;
 
 export class NodeTypingsInstaller extends ts.server.typingsInstaller.TypingsInstaller {
-    private readonly nodeExecSync: ExecSync;
     private readonly npmPath: string;
     readonly typesRegistry: Map<string, MapLike<string>>;
 
@@ -109,7 +108,6 @@ export class NodeTypingsInstaller extends ts.server.typingsInstaller.TypingsInst
             this.log.writeLine(`NPM location: ${this.npmPath} (explicit '${ts.server.Arguments.NpmLocation}' ${npmLocation === undefined ? "not " : ""} provided)`);
             this.log.writeLine(`validateDefaultNpmLocation: ${validateDefaultNpmLocation}`);
         }
-        ({ execSync: this.nodeExecSync } = require("child_process"));
 
         this.ensurePackageDirectoryExists(globalTypingsCacheLocation);
 
@@ -174,7 +172,7 @@ export class NodeTypingsInstaller extends ts.server.typingsInstaller.TypingsInst
             this.log.writeLine(`Exec: ${command}`);
         }
         try {
-            const stdout = this.nodeExecSync(command, { ...options, encoding: "utf-8" });
+            const stdout = execFileSync(command, { ...options, encoding: "utf-8" });
             if (this.log.isEnabled()) {
                 this.log.writeLine(`    Succeeded. stdout:${indent(sys.newLine, stdout)}`);
             }
diff --git a/testImportESM.mjs b/testImportESM.mjs
new file mode 100644
index 0000000000000..d4f29ec3a001a
--- /dev/null
+++ b/testImportESM.mjs
@@ -0,0 +1,5 @@
+import * as ts from "./built/local/typescript.js";
+import ts2 from "./built/local/typescript.js";
+
+console.log(ts.version);
+console.log(ts2.version);
diff --git a/testRequireESM.cjs b/testRequireESM.cjs
new file mode 100644
index 0000000000000..d6c1afae10252
--- /dev/null
+++ b/testRequireESM.cjs
@@ -0,0 +1,2 @@
+const ts = require("./built/local/typescript.js");
+console.log(ts.version);
diff --git a/tests/baselines/reference/APILibCheck.errors.txt b/tests/baselines/reference/APILibCheck.errors.txt
new file mode 100644
index 0000000000000..1dd48855ecd32
--- /dev/null
+++ b/tests/baselines/reference/APILibCheck.errors.txt
@@ -0,0 +1,48 @@
+tsserverlibrary.d.ts(17,15): error TS2498: Module '"typescript"' uses 'export =' and cannot be used with 'export *'.
+tsserverlibrary.internal.d.ts(17,15): error TS2498: Module '"typescript.internal"' uses 'export =' and cannot be used with 'export *'.
+
+
+==== node_modules/typescript/package.json (0 errors) ====
+    {
+        "name": "typescript",
+        "type": "module",
+        "exports": "./lib/typescript.d.ts"
+    }
+    
+==== node_modules/typescript-internal/package.json (0 errors) ====
+    {
+        "name": "typescript-internal",
+        "type": "module",
+        "exports": "./lib/typescript.internal.d.ts"
+    }
+    
+==== node_modules/tsserverlibrary/package.json (0 errors) ====
+    {
+        "name": "tsserverlibrary",
+        "type": "module",
+        "exports": "./lib/tsserverlibrary.d.ts"
+    }
+    
+==== node_modules/tsserverlibrary-internal/package.json (0 errors) ====
+    {
+        "name": "tsserverlibrary-internal",
+        "type": "module",
+        "exports": "./lib/tsserverlibrary.internal.d.ts"
+    }
+    
+==== package.json (0 errors) ====
+    {
+        "name": "project",
+        "type": "module"
+    }
+    
+==== index.ts (0 errors) ====
+    import * as ts from "typescript";
+    import tsDefault from "typescript";
+    import * as tsInternal from "typescript-internal";
+    import tsInternalDefault from "typescript-internal";
+    import * as tsserverlibrary from "tsserverlibrary";
+    import tsserverlibraryDefault from "tsserverlibrary";
+    import * as tsserverlibraryInternal from "tsserverlibrary-internal";
+    import tsserverlibraryInternalDefault from "tsserverlibrary-internal";
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/APILibCheck.js b/tests/baselines/reference/APILibCheck.js
index 76bacfbf7a675..4e5c1eeff1759 100644
--- a/tests/baselines/reference/APILibCheck.js
+++ b/tests/baselines/reference/APILibCheck.js
@@ -3,34 +3,47 @@
 //// [package.json]
 {
     "name": "typescript",
-    "types": "/.ts/typescript.d.ts"
+    "type": "module",
+    "exports": "./lib/typescript.d.ts"
 }
 
 //// [package.json]
 {
     "name": "typescript-internal",
-    "types": "/.ts/typescript.internal.d.ts"
+    "type": "module",
+    "exports": "./lib/typescript.internal.d.ts"
 }
 
 //// [package.json]
 {
     "name": "tsserverlibrary",
-    "types": "/.ts/tsserverlibrary.d.ts"
+    "type": "module",
+    "exports": "./lib/tsserverlibrary.d.ts"
 }
 
 //// [package.json]
 {
     "name": "tsserverlibrary-internal",
-    "types": "/.ts/tsserverlibrary.internal.d.ts"
+    "type": "module",
+    "exports": "./lib/tsserverlibrary.internal.d.ts"
+}
+
+//// [package.json]
+{
+    "name": "project",
+    "type": "module"
 }
 
 //// [index.ts]
-import ts = require("typescript");
-import tsInternal = require("typescript-internal");
-import tsserverlibrary = require("tsserverlibrary");
-import tsserverlibraryInternal = require("tsserverlibrary-internal");
+import * as ts from "typescript";
+import tsDefault from "typescript";
+import * as tsInternal from "typescript-internal";
+import tsInternalDefault from "typescript-internal";
+import * as tsserverlibrary from "tsserverlibrary";
+import tsserverlibraryDefault from "tsserverlibrary";
+import * as tsserverlibraryInternal from "tsserverlibrary-internal";
+import tsserverlibraryInternalDefault from "tsserverlibrary-internal";
 
 
 //// [index.js]
-"use strict";
-Object.defineProperty(exports, "__esModule", { value: true });
+export {};
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 3db5faa718232..5f60c7df8eeb4 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -13,5 +13,6 @@ See the Apache Version 2.0 License for specific language governing permissions
 and limitations under the License.
 ***************************************************************************** */
 
-import ts = require("./typescript.js");
-export = ts;
+import ts from "./typescript.js";
+export * from "./typescript.js";
+export default ts;
diff --git a/tests/cases/compiler/APILibCheck.ts b/tests/cases/compiler/APILibCheck.ts
index 7abf10e9821e9..c2805372e7106 100644
--- a/tests/cases/compiler/APILibCheck.ts
+++ b/tests/cases/compiler/APILibCheck.ts
@@ -1,36 +1,54 @@
-// @module: commonjs
+// @module: nodenext
 // @noImplicitAny: true
 // @strictNullChecks: true
 // @lib: es2018
 // @exactOptionalPropertyTypes: true
 // @noTypesAndSymbols: true
 
+// @link: /.ts/typescript.d.ts -> node_modules/typescript/lib/typescript.d.ts
 // @filename: node_modules/typescript/package.json
 {
     "name": "typescript",
-    "types": "/.ts/typescript.d.ts"
+    "type": "module",
+    "exports": "./lib/typescript.d.ts"
 }
 
+// @link: /.ts/typescript.internal.d.ts -> node_modules/typescript-internal/lib/typescript.internal.d.ts
 // @filename: node_modules/typescript-internal/package.json
 {
     "name": "typescript-internal",
-    "types": "/.ts/typescript.internal.d.ts"
+    "type": "module",
+    "exports": "./lib/typescript.internal.d.ts"
 }
 
+// @link: /.ts/tsserverlibrary.d.ts -> node_modules/tsserverlibrary/lib/tsserverlibrary.d.ts
 // @filename: node_modules/tsserverlibrary/package.json
 {
     "name": "tsserverlibrary",
-    "types": "/.ts/tsserverlibrary.d.ts"
+    "type": "module",
+    "exports": "./lib/tsserverlibrary.d.ts"
 }
 
+// @link: /.ts/tsserverlibrary.internal.d.ts -> node_modules/tsserverlibrary-internal/lib/tsserverlibrary.internal.d.ts
 // @filename: node_modules/tsserverlibrary-internal/package.json
 {
     "name": "tsserverlibrary-internal",
-    "types": "/.ts/tsserverlibrary.internal.d.ts"
+    "type": "module",
+    "exports": "./lib/tsserverlibrary.internal.d.ts"
+}
+
+// @filename: package.json
+{
+    "name": "project",
+    "type": "module"
 }
 
 // @filename: index.ts
-import ts = require("typescript");
-import tsInternal = require("typescript-internal");
-import tsserverlibrary = require("tsserverlibrary");
-import tsserverlibraryInternal = require("tsserverlibrary-internal");
+import * as ts from "typescript";
+import tsDefault from "typescript";
+import * as tsInternal from "typescript-internal";
+import tsInternalDefault from "typescript-internal";
+import * as tsserverlibrary from "tsserverlibrary";
+import tsserverlibraryDefault from "tsserverlibrary";
+import * as tsserverlibraryInternal from "tsserverlibrary-internal";
+import tsserverlibraryInternalDefault from "tsserverlibrary-internal";