avivkeller · Oct 17, 2026
diff --git a/doc/api/cli.md b/doc/api/cli.md
@@ -1742,14 +1742,6 @@ changes:
 
 Enable experimental WebAssembly System Interface (WASI) support.
 
-### `--experimental-web-worker`
-
-<!-- YAML
-added: v26.9.0
--->
-
-Enable experimental support for the Web Worker API.
-
 ### `--experimental-worker-inspection`
 
 <!-- YAML
@@ -2368,6 +2360,20 @@ changes:
 
 Disable the experimental [`node:vfs`][] module and `--vfs-load`.
 
+### `--no-experimental-web-worker`
+
+<!-- YAML
+added: v26.9.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/65323
+    description: This feature is now enabled by default.
+-->
+
+> Stability: 1.1 - Active Development
+
+Disable support for the Web Worker API.
+
 ### `--no-experimental-webstorage`
 
 <!-- YAML
@@ -4291,7 +4297,6 @@ one is included in the list below.
 * `--experimental-top-level-await`
 * `--experimental-vm-modules`
 * `--experimental-wasi-unstable-preview1`
-* `--experimental-web-worker`
 * `--experimental-websocket`
 * `--force-context-aware`
 * `--force-fips`
@@ -4324,6 +4329,7 @@ one is included in the list below.
 * `--no-experimental-sqlite`
 * `--no-experimental-strip-types`
 * `--no-experimental-vfs`
+* `--no-experimental-web-worker`
 * `--no-experimental-webstorage`
 * `--no-extra-info-on-fatal-exception`
 * `--no-force-async-hooks-checks`

diff --git a/doc/api/globals.md b/doc/api/globals.md
@@ -1320,10 +1320,14 @@ A browser-compatible implementation of {WebSocket}.
 
 <!-- YAML
 added: v26.9.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/65323
+    description: This feature is now enabled by default.
 -->
 
-> Stability: 1 - Experimental. Enable this API with the
-> [`--experimental-web-worker`][] CLI flag.
+> Stability: 1 - Experimental. Disable this API with the
+> [`--no-experimental-web-worker`][] CLI flag.
 
 A mostly browser-compatible implementation of Web Workers of the [HTML Standard][],
 implemented on top of [`node:worker_threads`][]. Threads created with it
@@ -1475,9 +1479,9 @@ A browser-compatible implementation of [`WritableStreamDefaultWriter`][].
 [Refable protocol]: process.md#processrefmayberefable
 [Web Crypto API]: webcrypto.md
 [`--experimental-eventsource`]: cli.md#--experimental-eventsource
-[`--experimental-web-worker`]: cli.md#--experimental-web-worker
 [`--localstorage-file`]: cli.md#--localstorage-filefile
 [`--no-experimental-global-navigator`]: cli.md#--no-experimental-global-navigator
+[`--no-experimental-web-worker`]: cli.md#--no-experimental-web-worker
 [`--no-experimental-webstorage`]: cli.md#--no-experimental-webstorage
 [`ByteLengthQueuingStrategy`]: webstreams.md#class-bytelengthqueuingstrategy
 [`CompressionStream`]: webstreams.md#class-compressionstream

diff --git a/doc/node.1 b/doc/node.1
@@ -938,9 +938,6 @@ Enable experimental ES Module support in the \fBnode:vm\fR module.
 .It Fl -experimental-wasi-unstable-preview1
 Enable experimental WebAssembly System Interface (WASI) support.
 .
-.It Fl -experimental-web-worker
-Enable experimental support for the Web Worker API.
-.
 .It Fl -experimental-worker-inspection
 Enable experimental support for the worker inspection with Chrome DevTools.
 .
@@ -1235,6 +1232,9 @@ Disable the experimental \fBnode:sqlite\fR module.
 .It Fl -no-experimental-vfs
 Disable the experimental \fBnode:vfs\fR module and \fB--vfs-load\fR.
 .
+.It Fl -no-experimental-web-worker
+Disable support for the Web Worker API.
+.
 .It Fl -no-experimental-webstorage
 Disable \fBWeb Storage\fR support.
 .
@@ -2281,8 +2281,6 @@ one is included in the list below.
 .It
 \fB--experimental-wasi-unstable-preview1\fR
 .It
-\fB--experimental-web-worker\fR
-.It
 \fB--experimental-websocket\fR
 .It
 \fB--force-context-aware\fR
@@ -2347,6 +2345,8 @@ one is included in the list below.
 .It
 \fB--no-experimental-vfs\fR
 .It
+\fB--no-experimental-web-worker\fR
+.It
 \fB--no-experimental-webstorage\fR
 .It
 \fB--no-extra-info-on-fatal-exception\fR

diff --git a/src/node_options.cc b/src/node_options.cc
@@ -788,7 +788,7 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "experimental Web Worker API",
             BOOL_FIELD(experimental_web_worker),
             kAllowedInEnvvar,
-            false);
+            true);
   AddOption("--experimental-websocket", "", NoOp{}, kAllowedInEnvvar);
   AddOption("--experimental-global-customevent", "", NoOp{}, kAllowedInEnvvar);
   AddOption("--experimental-sqlite",

diff --git a/src/node_options.h b/src/node_options.h
@@ -211,7 +211,7 @@ class EnvironmentOptions : public Options {
   DEFINE_BOOL_FIELD(experimental_bench) = EXPERIMENTALS_DEFAULT_VALUE;
   DEFINE_BOOL_FIELD(experimental_eventsource) = EXPERIMENTALS_DEFAULT_VALUE;
   DEFINE_BOOL_FIELD(experimental_ffi) = HAVE_FFI;
-  DEFINE_BOOL_FIELD(experimental_web_worker) = EXPERIMENTALS_DEFAULT_VALUE;
+  DEFINE_BOOL_FIELD(experimental_web_worker) = true;
   DEFINE_BOOL_FIELD(experimental_websocket) = true;
   DEFINE_BOOL_FIELD(experimental_sqlite) = HAVE_SQLITE;
   DEFINE_BOOL_FIELD(experimental_stream_iter) = EXPERIMENTALS_DEFAULT_VALUE;

diff --git a/test/common/wpt.js b/test/common/wpt.js
@@ -865,11 +865,7 @@ class WPTRunner {
     this.resource = new ResourceLoader(path);
     this.concurrency = concurrency;
 
-    // Since we need to prepare the Web Worker APIs
-    // in the harness that runs on all WPT workers,
-    // we enable the API globally. This has no practical
-    // effect on the non-web-worker tests, however.
-    this.flags = ['--experimental-web-worker'];
+    this.flags = [];
     if (this.inspectBrk) {
       this.flags.push('--inspect-brk=0');
     }

diff --git a/test/parallel/test-common-wpt-allowed-rejections.js b/test/parallel/test-common-wpt-allowed-rejections.js
@@ -45,7 +45,7 @@ async function check(backend, webWorker, {
 
   let result;
   const statuses = [];
-  const handle = backends[backend](['--experimental-web-worker'], workerData, {
+  const handle = backends[backend]([], workerData, {
     message(message) {
       if (message.type === 'result') {
         statuses.push(message.result.status);

diff --git a/test/parallel/test-common-wpt-backends.js b/test/parallel/test-common-wpt-backends.js
@@ -18,7 +18,7 @@ const backendProbe = process.env.NODE_TEST_WPT_BACKEND_PROBE;
 
 const harnessPath = fixtures.path('wpt', 'resources', 'testharness.js');
 const specPath = fixtures.path('wpt-backends-spec.js');
-const execArgv = ['--experimental-web-worker'];
+const execArgv = [];
 
 function payload(throws) {
   return {

diff --git a/test/parallel/test-common-wpt-webworker-error.js b/test/parallel/test-common-wpt-webworker-error.js
@@ -10,7 +10,7 @@ const { Worker } = require('worker_threads');
 
 const workerPath = path.join(__dirname, '../common/wpt/worker.js');
 const harnessPath = fixtures.path('wpt', 'resources', 'testharness.js');
-const execArgv = ['--experimental-web-worker'];
+const execArgv = [];
 const workerData = {
   testRelativePath: 'workers/error-after-result.any.js',
   wptRunner: path.join(__dirname, '../common/wpt.js'),

diff --git a/test/parallel/test-webworker-blob-module-url.js b/test/parallel/test-webworker-blob-module-url.js
@@ -1,4 +1,3 @@
-// Flags: --experimental-web-worker
 'use strict';
 
 const common = require('../common');

diff --git a/test/parallel/test-webworker-disabled.js b/test/parallel/test-webworker-disabled.js
@@ -0,0 +1,10 @@
+// Flags: --no-experimental-web-worker
+'use strict';
+
+// The Web Worker API is enabled by default, but can be opted out of.
+// Refs: https://github.com/nodejs/node/pull/65323
+
+require('../common');
+const assert = require('assert');
+
+assert.strictEqual(typeof Worker, 'undefined');
diff --git a/test/parallel/test-webworker-enabled-by-default.js b/test/parallel/test-webworker-enabled-by-default.js
@@ -0,0 +1,13 @@
+'use strict';
+
+// Regression test: the Web Worker API is enabled by default and must not
+// require the `--experimental-web-worker` flag.
+// Refs: https://github.com/nodejs/node/pull/65323
+
+require('../common');
+const assert = require('assert');
+const { Worker: WorkerThread } = require('worker_threads');
+
+assert.strictEqual(typeof Worker, 'function');
+assert.strictEqual(Worker.name, 'Worker');
+assert.notStrictEqual(Worker, WorkerThread);
diff --git a/test/parallel/test-webworker-importscripts-conversion.js b/test/parallel/test-webworker-importscripts-conversion.js
@@ -1,4 +1,3 @@
-// Flags: --experimental-web-worker
 'use strict';
 
 const common = require('../common');

diff --git a/test/parallel/test-webworker-postmessage-lifecycle.js b/test/parallel/test-webworker-postmessage-lifecycle.js
@@ -1,4 +1,3 @@
-// Flags: --experimental-web-worker
 'use strict';
 
 const common = require('../common');

diff --git a/test/parallel/test-webworker-postmessage-overloads.js b/test/parallel/test-webworker-postmessage-overloads.js
@@ -1,4 +1,3 @@
-// Flags: --experimental-web-worker
 'use strict';
 
 const common = require('../common');

diff --git a/test/parallel/test-webworker-ref-unref.js b/test/parallel/test-webworker-ref-unref.js
@@ -1,4 +1,3 @@
-// Flags: --experimental-web-worker
 'use strict';
 
 const common = require('../common');

diff --git a/test/parallel/test-webworker-typescript-disabled.js b/test/parallel/test-webworker-typescript-disabled.js
@@ -1,4 +1,4 @@
-// Flags: --experimental-web-worker --no-strip-types
+// Flags: --no-strip-types
 'use strict';
 
 const common = require('../common');

diff --git a/test/parallel/test-webworker-typescript.js b/test/parallel/test-webworker-typescript.js
@@ -1,4 +1,3 @@
-// Flags: --experimental-web-worker
 'use strict';
 
 const common = require('../common');

diff --git a/test/parallel/test-worker-spec-differences.js b/test/parallel/test-worker-spec-differences.js
@@ -1,4 +1,3 @@
-// Flags: --experimental-web-worker
 'use strict';
 
 const common = require('../common');