diff --git a/packages/playwright-client/build.js b/packages/playwright-client/build.js
new file mode 100644
index 0000000000..0b7213708d
--- /dev/null
+++ b/packages/playwright-client/build.js
@@ -0,0 +1,51 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// @ts-check
+const path = require('path');
+const esbuild = require('esbuild');
+
+
+/**
+ * @param {boolean} watchMode
+ * @returns {import('esbuild').BuildOptions}
+ */
+function esbuildOptions(watchMode) {
+  return {
+    entryPoints: [path.join(__dirname, 'src/index.ts')],
+    bundle: true,
+    outdir: path.join(__dirname, 'lib'),
+    format: 'cjs',
+    platform: 'node',
+    target: 'ES2019',
+    sourcemap: watchMode,
+  };
+}
+
+async function main() {
+  const watchMode = process.argv.includes('--watch');
+  const ctx = await esbuild.context(esbuildOptions(watchMode));
+  await ctx.rebuild();
+  if (watchMode)
+    await ctx.watch();
+  else
+    await ctx.dispose();
+}
+
+module.exports = { esbuildOptions };
+
+if (require.main === module)
+  main();
diff --git a/packages/playwright-client/package.json b/packages/playwright-client/package.json
index 16dbee8b58..f2a834e2fa 100644
--- a/packages/playwright-client/package.json
+++ b/packages/playwright-client/package.json
@@ -25,8 +25,9 @@
     "./package.json": "./package.json"
   },
   "scripts": {
-    "build": "esbuild ./src/index.ts --outdir=lib --format=cjs --bundle --platform=node --target=ES2019",
-    "watch": "esbuild ./src/index.ts --outdir=lib --format=cjs --bundle --platform=node --target=ES2019 --watch"
+    "esbuild": "node build.js",
+    "build": "npm run esbuild",
+    "watch": "npm run esbuild -- --watch"
   },
   "dependencies": {
     "playwright-core": "1.53.0-next"
diff --git a/packages/playwright-core/bundles/utils/build.js b/packages/playwright-core/bundles/utils/build.js
index c14196668a..fbd276deb5 100644
--- a/packages/playwright-core/bundles/utils/build.js
+++ b/packages/playwright-core/bundles/utils/build.js
@@ -21,31 +21,47 @@ const fs = require('fs');
 
 const outdir = path.join(__dirname, '../../lib/utilsBundleImpl');
 
-if (!fs.existsSync(outdir))
-  fs.mkdirSync(outdir);
+function copyXdgOpen() {
+  if (!fs.existsSync(outdir))
+    fs.mkdirSync(outdir, { recursive: true });
 
-{
   // 'open' package requires 'xdg-open' binary to be present, which does not get bundled by esbuild.
   fs.copyFileSync(path.join(__dirname, 'node_modules/open/xdg-open'), path.join(outdir, 'xdg-open'));
+  console.log('==== Copied xdg-open to', path.join(outdir, 'xdg-open'));
 }
 
-(async () => {
-  const ctx = await esbuild.context({
+/**
+ * @param {boolean} watchMode
+ * @returns {import('esbuild').BuildOptions}
+ */
+function esbuildOptions(watchMode) {
+  return {
     entryPoints: [path.join(__dirname, 'src/utilsBundleImpl.ts')],
     bundle: true,
     outfile: path.join(outdir, 'index.js'),
     format: 'cjs',
     platform: 'node',
     target: 'ES2019',
-    sourcemap: process.argv.includes('--sourcemap'),
-    minify: process.argv.includes('--minify'),
-  });
+    sourcemap: watchMode,
+    minify: !watchMode,
+  };
+}
+
+async function main() {
+  copyXdgOpen();
+  const watchMode = process.argv.includes('--watch');
+  const ctx = await esbuild.context(esbuildOptions(watchMode));
   await ctx.rebuild();
-  if (process.argv.includes('--watch'))
+  if (watchMode)
     await ctx.watch();
   else
     await ctx.dispose();
-})().catch(error => {
-  console.error(error);
-  process.exit(1);
-});
+}
+
+module.exports = {
+  beforeEsbuild: copyXdgOpen,
+  esbuildOptions,
+};
+
+if (require.main === module)
+  main();
diff --git a/packages/playwright-core/bundles/utils/package.json b/packages/playwright-core/bundles/utils/package.json
index e7f09cf3a0..4944b7b078 100644
--- a/packages/playwright-core/bundles/utils/package.json
+++ b/packages/playwright-core/bundles/utils/package.json
@@ -4,8 +4,8 @@
   "private": true,
   "scripts": {
     "esbuild": "node build.js",
-    "build": "npm run esbuild -- --minify",
-    "watch": "npm run esbuild -- --watch --sourcemap",
+    "build": "npm run esbuild",
+    "watch": "npm run esbuild -- --watch",
     "generate-license": "node ../../../../utils/generate_third_party_notice.js"
   },
   "dependencies": {
diff --git a/packages/playwright-core/bundles/zip/build.js b/packages/playwright-core/bundles/zip/build.js
index 6efadad71c..5eb79c66d8 100644
--- a/packages/playwright-core/bundles/zip/build.js
+++ b/packages/playwright-core/bundles/zip/build.js
@@ -18,23 +18,34 @@
 const path = require('path');
 const esbuild = require('esbuild');
 
-(async () => {
-  const ctx = await esbuild.context({
+/**
+ * @param {boolean} watchMode
+ * @returns {import('esbuild').BuildOptions}
+ */
+function esbuildOptions(watchMode) {
+  return {
     entryPoints: [path.join(__dirname, 'src/zipBundleImpl.ts')],
     bundle: true,
     outdir: path.join(__dirname, '../../lib'),
     format: 'cjs',
     platform: 'node',
     target: 'ES2019',
-    sourcemap: process.argv.includes('--sourcemap'),
-    minify: process.argv.includes('--minify'),
-  });
+    sourcemap: watchMode,
+    minify: !watchMode,
+  };
+}
+
+async function main() {
+  const watchMode = process.argv.includes('--watch');
+  const ctx = await esbuild.context(esbuildOptions(watchMode));
   await ctx.rebuild();
-  if (process.argv.includes('--watch'))
+  if (watchMode)
     await ctx.watch();
   else
     await ctx.dispose();
-})().catch(error => {
-  console.error(error);
-  process.exit(1);
-});
+}
+
+module.exports = { esbuildOptions };
+
+if (require.main === module)
+  main();
diff --git a/packages/playwright-core/bundles/zip/package.json b/packages/playwright-core/bundles/zip/package.json
index 64f75f7195..3e0124035b 100644
--- a/packages/playwright-core/bundles/zip/package.json
+++ b/packages/playwright-core/bundles/zip/package.json
@@ -4,8 +4,8 @@
   "private": true,
   "scripts": {
     "esbuild": "node build.js",
-    "build": "npm run esbuild -- --minify",
-    "watch": "npm run esbuild -- --watch --sourcemap",
+    "build": "npm run esbuild",
+    "watch": "npm run esbuild -- --watch",
     "generate-license": "node ../../../../utils/generate_third_party_notice.js"
   },
   "dependencies": {
diff --git a/packages/playwright/bundles/babel/build.js b/packages/playwright/bundles/babel/build.js
new file mode 100644
index 0000000000..c5cffa4baa
--- /dev/null
+++ b/packages/playwright/bundles/babel/build.js
@@ -0,0 +1,52 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// @ts-check
+const path = require('path');
+const esbuild = require('esbuild');
+
+/**
+ * @param {boolean} watchMode
+ * @returns {import('esbuild').BuildOptions}
+ */
+function esbuildOptions(watchMode) {
+  return {
+    entryPoints: [path.join(__dirname, 'src/babelBundleImpl.ts')],
+    external: ['playwright'],
+    bundle: true,
+    outdir: path.join(__dirname, '../../lib/transform'),
+    format: 'cjs',
+    platform: 'node',
+    target: 'ES2019',
+    sourcemap: watchMode,
+    minify: !watchMode,
+  };
+}
+
+async function main() {
+  const watchMode = process.argv.includes('--watch');
+  const ctx = await esbuild.context(esbuildOptions(watchMode));
+  await ctx.rebuild();
+  if (watchMode)
+    await ctx.watch();
+  else
+    await ctx.dispose();
+}
+
+module.exports = { esbuildOptions };
+
+if (require.main === module)
+  main();
diff --git a/packages/playwright/bundles/babel/package.json b/packages/playwright/bundles/babel/package.json
index fca7b43012..969026a81a 100644
--- a/packages/playwright/bundles/babel/package.json
+++ b/packages/playwright/bundles/babel/package.json
@@ -3,9 +3,9 @@
   "version": "0.0.1",
   "private": true,
   "scripts": {
-    "esbuild": "esbuild ./src/babelBundleImpl.ts --bundle --outdir=../../lib/transform --format=cjs --platform=node --target=ES2019 --external:playwright",
-    "build": "npm run esbuild -- --minify",
-    "watch": "npm run esbuild -- --watch --sourcemap",
+    "esbuild": "node build.js",
+    "build": "npm run esbuild",
+    "watch": "npm run esbuild -- --watch",
     "generate-license": "node ../../../../utils/generate_third_party_notice.js"
   },
   "dependencies": {
diff --git a/packages/playwright/bundles/expect/build.js b/packages/playwright/bundles/expect/build.js
new file mode 100644
index 0000000000..18a37f60c8
--- /dev/null
+++ b/packages/playwright/bundles/expect/build.js
@@ -0,0 +1,51 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// @ts-check
+const path = require('path');
+const esbuild = require('esbuild');
+
+/**
+ * @param {boolean} watchMode
+ * @returns {import('esbuild').BuildOptions}
+ */
+function esbuildOptions(watchMode) {
+  return {
+    entryPoints: [path.join(__dirname, 'src/expectBundleImpl.ts')],
+    bundle: true,
+    outdir: path.join(__dirname, '../../lib/common'),
+    format: 'cjs',
+    platform: 'node',
+    target: 'ES2019',
+    sourcemap: watchMode,
+    minify: !watchMode,
+  };
+}
+
+async function main() {
+  const watchMode = process.argv.includes('--watch');
+  const ctx = await esbuild.context(esbuildOptions(watchMode));
+  await ctx.rebuild();
+  if (watchMode)
+    await ctx.watch();
+  else
+    await ctx.dispose();
+}
+
+module.exports = { esbuildOptions };
+
+if (require.main === module)
+  main();
diff --git a/packages/playwright/bundles/expect/package.json b/packages/playwright/bundles/expect/package.json
index d9f436755f..3ce2d05ecc 100644
--- a/packages/playwright/bundles/expect/package.json
+++ b/packages/playwright/bundles/expect/package.json
@@ -3,9 +3,9 @@
   "version": "0.0.1",
   "private": true,
   "scripts": {
-    "esbuild": "esbuild ./src/expectBundleImpl.ts --bundle --outdir=../../lib/common --format=cjs --platform=node --target=ES2019",
-    "build": "npm run esbuild -- --minify",
-    "watch": "npm run esbuild -- --watch --sourcemap",
+    "esbuild": "node build.js",
+    "build": "npm run esbuild",
+    "watch": "npm run esbuild -- --watch",
     "generate-license": "node ../../../../utils/generate_third_party_notice.js"
   },
   "dependencies": {
diff --git a/packages/playwright/bundles/utils/build.js b/packages/playwright/bundles/utils/build.js
index 1feb97ea26..8bd29d74f7 100644
--- a/packages/playwright/bundles/utils/build.js
+++ b/packages/playwright/bundles/utils/build.js
@@ -18,8 +18,12 @@
 const path = require('path');
 const esbuild = require('esbuild');
 
-(async () => {
-  const ctx = await esbuild.context({
+/**
+ * @param {boolean} watchMode
+ * @returns {import('esbuild').BuildOptions}
+ */
+function esbuildOptions(watchMode) {
+  return {
     entryPoints: [path.join(__dirname, 'src/utilsBundleImpl.ts')],
     external: ['fsevents'],
     bundle: true,
@@ -27,15 +31,22 @@ const esbuild = require('esbuild');
     format: 'cjs',
     platform: 'node',
     target: 'ES2019',
-    sourcemap: process.argv.includes('--sourcemap'),
-    minify: process.argv.includes('--minify'),
-  });
+    sourcemap: watchMode,
+    minify: !watchMode,
+  };
+}
+
+async function main() {
+  const watchMode = process.argv.includes('--watch');
+  const ctx = await esbuild.context(esbuildOptions(watchMode));
   await ctx.rebuild();
-  if (process.argv.includes('--watch'))
+  if (watchMode)
     await ctx.watch();
   else
     await ctx.dispose();
-})().catch(error => {
-  console.error(error);
-  process.exit(1);
-});
+}
+
+module.exports = { esbuildOptions };
+
+if (require.main === module)
+  main();
diff --git a/packages/playwright/bundles/utils/package.json b/packages/playwright/bundles/utils/package.json
index 3fb09c1d17..63ee4858bb 100644
--- a/packages/playwright/bundles/utils/package.json
+++ b/packages/playwright/bundles/utils/package.json
@@ -4,8 +4,8 @@
   "private": true,
   "scripts": {
     "esbuild": "node build.js",
-    "build": "npm run esbuild -- --minify",
-    "watch": "npm run esbuild -- --watch --sourcemap",
+    "build": "npm run esbuild",
+    "watch": "npm run esbuild -- --watch",
     "generate-license": "node ../../../../utils/generate_third_party_notice.js"
   },
   "dependencies": {
diff --git a/utils/build/build.js b/utils/build/build.js
index fc21ba10b1..28ab8975dd 100644
--- a/utils/build/build.js
+++ b/utils/build/build.js
@@ -67,8 +67,7 @@ const onChanges = [];
 const copyFiles = [];
 
 const watchMode = process.argv.slice(2).includes('--watch');
-const lintMode = process.argv.slice(2).includes('--lint');
-const withSourceMaps = process.argv.slice(2).includes('--sourcemap') || watchMode;
+const withSourceMaps = watchMode;
 const installMode = process.argv.slice(2).includes('--install');
 const ROOT = path.join(__dirname, '..', '..');
 
@@ -292,7 +291,7 @@ class EsbuildStep extends Step {
     if (watchMode) {
       await this._ensureWatching();
     } else {
-      console.log('==== Running esbuild', this._options.entryPoints.map(e => path.relative(ROOT, e)).join(', '));
+      console.log('==== Running esbuild:', this._relativeEntryPoints().join(', '));
       const start = Date.now();
       await build(this._options);
       console.log('==== Done in', Date.now() - start, 'ms');
@@ -311,7 +310,7 @@ class EsbuildStep extends Step {
     watcher.on('all', () => this._rebuild());
 
     await this._rebuild();
-    console.log('==== Esbuild watching', this._options.entryPoints, `(started in ${Date.now() - start}ms)`);
+    console.log('==== Esbuild watching:', this._relativeEntryPoints().join(', '), `(started in ${Date.now() - start}ms)`);
   }
 
   async _rebuild() {
@@ -332,15 +331,32 @@ class EsbuildStep extends Step {
       this._rebuilding = false;
     } while (this._sourcesChanged);
   }
+
+  _relativeEntryPoints() {
+    return this._options.entryPoints.map(e => path.relative(ROOT, e));
+  }
+}
+
+class CustomCallbackStep extends Step {
+  constructor(callback) {
+    super({ concurrent: false });
+    this._callback = callback;
+  }
+
+  async run() {
+    await this._callback();
+  }
 }
 
 // Run esbuild.
 for (const pkg of workspace.packages()) {
   if (!fs.existsSync(path.join(pkg.path, 'src')))
     continue;
-  // These packages have their own build step.
-  if (['@playwright/client'].includes(pkg.name))
+  // playwright-client has its own build step.
+  if (['@playwright/client'].includes(pkg.name)) {
+    loadBundleEsbuildStep(pkg.path);
     continue;
+  }
 
   steps.push(new EsbuildStep({
     entryPoints: [path.join(pkg.path, 'src/**/*.ts')],
@@ -352,32 +368,19 @@ for (const pkg of workspace.packages()) {
 }
 
 // Build/watch bundles.
-for (const bundle of bundles) {
-  steps.push(new ProgramStep({
-    command: 'npm',
-    args: [
-      'run',
-      watchMode ? 'watch' : 'build',
-      ...(withSourceMaps ? ['--', '--sourcemap'] : [])
-    ],
-    shell: true,
-    cwd: bundle,
-    concurrent: true,
-  }));
-}
+for (const bundle of bundles)
+  loadBundleEsbuildStep(bundle);
 
-// Build/watch playwright-client.
-steps.push(new ProgramStep({
-  command: 'npm',
-  args: [
-    'run',
-    watchMode ? 'watch' : 'build',
-    ...(withSourceMaps ? ['--', '--sourcemap'] : [])
-  ],
-  shell: true,
-  cwd: path.join(__dirname, '..', '..', 'packages', 'playwright-client'),
-  concurrent: true,
-}));
+function loadBundleEsbuildStep(bundle) {
+  const buildFile = path.join(bundle, 'build.js');
+  if (!fs.existsSync(buildFile))
+    throw new Error(`Build file ${buildFile} does not exist`);
+  const { esbuildOptions, beforeEsbuild } = require(buildFile);
+  if (beforeEsbuild)
+    steps.push(new CustomCallbackStep(beforeEsbuild));
+  const options = esbuildOptions(watchMode);
+  steps.push(new EsbuildStep(options));
+}
 
 // Build/watch trace viewer service worker.
 steps.push(new ProgramStep({
@@ -528,7 +531,7 @@ copyFiles.push({
   to: 'packages/playwright-core/lib',
 });
 
-if (lintMode) {
+if (watchMode) {
   // Run TypeScript for type checking.
   steps.push(new ProgramStep({
     command: 'npx',