diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/404.html b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/404.html
new file mode 100644
index 000000000000..7bcd6c0f7147
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/404.html
@@ -0,0 +1 @@
+404.html
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/css/styles.css b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/css/styles.css
new file mode 100644
index 000000000000..5bce0aa11833
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/css/styles.css
@@ -0,0 +1 @@
+assets/css/styles.css
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/files/document.pdf b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/files/document.pdf
new file mode 100644
index 000000000000..cadc432f2545
Binary files /dev/null and b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/files/document.pdf differ
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/files/main.c b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/files/main.c
new file mode 100644
index 000000000000..e5a13d14fdf9
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/files/main.c
@@ -0,0 +1 @@
+assets/files/main.c
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/fonts/font.woff2 b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/fonts/font.woff2
new file mode 100644
index 000000000000..d32448578df1
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/fonts/font.woff2
@@ -0,0 +1 @@
+assets/fonts/font.woff2
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/images/photo.jpeg b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/images/photo.jpeg
new file mode 100644
index 000000000000..233fd1f21999
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/assets/images/photo.jpeg
@@ -0,0 +1 @@
+assets/images/photo.jpeg
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/both.html b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/both.html
new file mode 100644
index 000000000000..98fe32c3e37a
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/both.html
@@ -0,0 +1 @@
+both.html
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/both/index.html b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/both/index.html
new file mode 100644
index 000000000000..29f8d82f6055
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/both/index.html
@@ -0,0 +1 @@
+both/index.html
diff --git "a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/caf\303\251.html" "b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/caf\303\251.html"
new file mode 100644
index 000000000000..29a666b1d191
--- /dev/null
+++ "b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/caf\303\251.html"
@@ -0,0 +1 @@
+café.html
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/docs/2.x/index.html b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/docs/2.x/index.html
new file mode 100644
index 000000000000..ab659e0512d7
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/docs/2.x/index.html
@@ -0,0 +1 @@
+docs/2.x/index.html
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/file.html b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/file.html
new file mode 100644
index 000000000000..e9e7c7fc7ea2
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/file.html
@@ -0,0 +1 @@
+file.html
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/folder/index.html b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/folder/index.html
new file mode 100644
index 000000000000..299ace561c23
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/folder/index.html
@@ -0,0 +1 @@
+folder/index.html
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/index.html b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/index.html
new file mode 100644
index 000000000000..dcaf71693e4a
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/index.html
@@ -0,0 +1 @@
+index.html
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/site.webmanifest b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/site.webmanifest
new file mode 100644
index 000000000000..d647982bbf34
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/site.webmanifest
@@ -0,0 +1 @@
+site.webmanifest
diff --git a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/with space.html b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/with space.html
new file mode 100644
index 000000000000..8fc503d9c5dd
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/with space.html	
@@ -0,0 +1 @@
+with space.html
diff --git "a/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/\321\204\320\260\320\271\320\273.html" "b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/\321\204\320\260\320\271\320\273.html"
new file mode 100644
index 000000000000..bbceaa143181
--- /dev/null
+++ "b/packages/docusaurus/src/commands/serve/__tests__/__fixtures__/build/\321\204\320\260\320\271\320\273.html"
@@ -0,0 +1 @@
+файл.html
diff --git a/packages/docusaurus/src/commands/serve/__tests__/requestHandler.test.ts b/packages/docusaurus/src/commands/serve/__tests__/requestHandler.test.ts
new file mode 100644
index 000000000000..0a3e5893deec
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/requestHandler.test.ts
@@ -0,0 +1,527 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {describe, expect, it} from 'vitest';
+import {
+  describeRequests,
+  describeServing,
+  serveRequest,
+  type ServeOptions,
+} from './testUtils';
+
+// Appended to the baseUrl. The fixture build extends the static deployment of
+// https://github.com/slorber/trailing-slash-guide
+const RequestPaths = [
+  '/',
+  '/index',
+  '/index.html',
+
+  '/file',
+  '/file/',
+  '/file.html',
+
+  '/folder',
+  '/folder/',
+  '/folder/index',
+  '/folder/index.html',
+
+  '/both',
+  '/both/',
+  '/both.html',
+  '/both/index.html',
+
+  // A folder with a dot, like a docs version
+  '/docs/2.x',
+  '/docs/2.x/',
+
+  '/assets/css/styles.css',
+  '/assets/css/styles.css?v=1',
+  '/assets/',
+  // Extensions of 1, 3, 4, 5 and 11 characters
+  '/assets/files/main.c',
+  '/assets/files/document.pdf',
+  '/assets/images/photo.jpeg',
+  '/assets/fonts/font.woff2',
+  '/site.webmanifest',
+
+  '/missing',
+  '/missing/',
+  '/missing.html',
+
+  '/file?query=1',
+  '/file/?query=1',
+  '/file.html?query=1',
+  '/folder?query=1',
+
+  '/with%20space',
+  '/with%20space.html',
+  '/файл',
+  '/файл.html',
+  '/café',
+
+  '//file',
+  '/%E0%A4%A', // Malformed percent-encoding
+  // cspell:ignore Fdocusaurus
+  '/..%2Fdocusaurus.config.js', // Path traversal
+];
+
+describe('createServeRequestHandler', () => {
+  describe('baseUrl /', () => {
+    it('trailingSlash undefined', async () => {
+      const result = await describeServing(
+        {baseUrl: '/', trailingSlash: undefined},
+        RequestPaths,
+      );
+      expect(result).toMatchInlineSnapshot(`
+        "/                           200 index.html
+        /index                      301 / → 200 index.html
+        /index.html                 301 /index → 301 / → 200 index.html
+        /file                       200 file.html
+        /file/                      200 file.html
+        /file.html                  301 /file → 200 file.html
+        /folder                     200 folder/index.html
+        /folder/                    200 folder/index.html
+        /folder/index               301 /folder → 200 folder/index.html
+        /folder/index.html          301 /folder/index → 301 /folder → 200 folder/index.html
+        /both                       200 both/index.html
+        /both/                      200 both/index.html
+        /both.html                  301 /both → 200 both/index.html
+        /both/index.html            301 /both/index → 301 /both → 200 both/index.html
+        /docs/2.x                   404 404.html
+        /docs/2.x/                  404 404.html
+        /assets/css/styles.css      200 assets/css/styles.css
+        /assets/css/styles.css?v=1  200 assets/css/styles.css
+        /assets/                    404 404.html
+        /assets/files/main.c        200 assets/files/main.c
+        /assets/files/document.pdf  200 assets/files/document.pdf
+        /assets/images/photo.jpeg   200 assets/images/photo.jpeg
+        /assets/fonts/font.woff2    200 assets/fonts/font.woff2
+        /site.webmanifest           200 site.webmanifest
+        /missing                    404 404.html
+        /missing/                   404 404.html
+        /missing.html               301 /missing → 404 404.html
+        /file?query=1               200 file.html
+        /file/?query=1              200 file.html
+        /file.html?query=1          301 /file → 200 file.html
+        /folder?query=1             200 folder/index.html
+        /with%20space               200 with space.html
+        /with%20space.html          301 /with%20space → 200 with space.html
+        /файл                       200 файл.html
+        /файл.html                  301 /%D1%84%D0%B0%D0%B9%D0%BB → 200 файл.html
+        /café                       crash ERR_INVALID_CHAR
+        //file                      200 file.html
+        /%E0%A4%A                   400 Bad Request
+        /..%2Fdocusaurus.config.js  400 Bad Request"
+      `);
+    });
+
+    it('trailingSlash true', async () => {
+      const result = await describeServing(
+        {baseUrl: '/', trailingSlash: true},
+        RequestPaths,
+      );
+      expect(result).toMatchInlineSnapshot(`
+        "/                           200 index.html
+        /index                      301 / → 200 index.html
+        /index.html                 301 /index → 301 / → 200 index.html
+        /file                       301 /file/ → 200 file.html
+        /file/                      200 file.html
+        /file.html                  301 /file → 301 /file/ → 200 file.html
+        /folder                     301 /folder/ → 200 folder/index.html
+        /folder/                    200 folder/index.html
+        /folder/index               301 /folder → 301 /folder/ → 200 folder/index.html
+        /folder/index.html          301 /folder/index → 301 /folder → 301 /folder/ → 200 folder/index.html
+        /both                       301 /both/ → 200 both/index.html
+        /both/                      200 both/index.html
+        /both.html                  301 /both → 301 /both/ → 200 both/index.html
+        /both/index.html            301 /both/index → 301 /both → 301 /both/ → 200 both/index.html
+        /docs/2.x                   404 404.html
+        /docs/2.x/                  404 404.html
+        /assets/css/styles.css      200 assets/css/styles.css
+        /assets/css/styles.css?v=1  200 assets/css/styles.css
+        /assets/                    404 404.html
+        /assets/files/main.c        200 assets/files/main.c
+        /assets/files/document.pdf  200 assets/files/document.pdf
+        /assets/images/photo.jpeg   200 assets/images/photo.jpeg
+        /assets/fonts/font.woff2    200 assets/fonts/font.woff2
+        /site.webmanifest           200 site.webmanifest
+        /missing                    301 /missing/ → 404 404.html
+        /missing/                   404 404.html
+        /missing.html               301 /missing → 301 /missing/ → 404 404.html
+        /file?query=1               301 /file/ → 200 file.html
+        /file/?query=1              200 file.html
+        /file.html?query=1          301 /file → 301 /file/ → 200 file.html
+        /folder?query=1             301 /folder/ → 200 folder/index.html
+        /with%20space               301 /with%20space/ → 200 with space.html
+        /with%20space.html          301 /with%20space → 301 /with%20space/ → 200 with space.html
+        /файл                       301 /%D1%84%D0%B0%D0%B9%D0%BB/ → 200 файл.html
+        /файл.html                  301 /%D1%84%D0%B0%D0%B9%D0%BB → 301 /%D1%84%D0%B0%D0%B9%D0%BB/ → 200 файл.html
+        /café                       301 /caf%C3%A9/ → crash ERR_INVALID_CHAR
+        //file                      301 /file → 301 /file/ → 200 file.html
+        /%E0%A4%A                   400 Bad Request
+        /..%2Fdocusaurus.config.js  400 Bad Request"
+      `);
+    });
+
+    it('trailingSlash false', async () => {
+      const result = await describeServing(
+        {baseUrl: '/', trailingSlash: false},
+        RequestPaths,
+      );
+      expect(result).toMatchInlineSnapshot(`
+        "/                           200 index.html
+        /index                      301 / → 200 index.html
+        /index.html                 301 /index → 301 / → 200 index.html
+        /file                       200 file.html
+        /file/                      301 /file → 200 file.html
+        /file.html                  301 /file → 200 file.html
+        /folder                     200 folder/index.html
+        /folder/                    301 /folder → 200 folder/index.html
+        /folder/index               301 /folder → 200 folder/index.html
+        /folder/index.html          301 /folder/index → 301 /folder → 200 folder/index.html
+        /both                       200 both/index.html
+        /both/                      301 /both → 200 both/index.html
+        /both.html                  301 /both → 200 both/index.html
+        /both/index.html            301 /both/index → 301 /both → 200 both/index.html
+        /docs/2.x                   404 404.html
+        /docs/2.x/                  301 /docs/2.x → 404 404.html
+        /assets/css/styles.css      200 assets/css/styles.css
+        /assets/css/styles.css?v=1  200 assets/css/styles.css
+        /assets/                    301 /assets → 404 404.html
+        /assets/files/main.c        200 assets/files/main.c
+        /assets/files/document.pdf  200 assets/files/document.pdf
+        /assets/images/photo.jpeg   200 assets/images/photo.jpeg
+        /assets/fonts/font.woff2    200 assets/fonts/font.woff2
+        /site.webmanifest           200 site.webmanifest
+        /missing                    404 404.html
+        /missing/                   301 /missing → 404 404.html
+        /missing.html               301 /missing → 404 404.html
+        /file?query=1               200 file.html
+        /file/?query=1              301 /file → 200 file.html
+        /file.html?query=1          301 /file → 200 file.html
+        /folder?query=1             200 folder/index.html
+        /with%20space               200 with space.html
+        /with%20space.html          301 /with%20space → 200 with space.html
+        /файл                       200 файл.html
+        /файл.html                  301 /%D1%84%D0%B0%D0%B9%D0%BB → 200 файл.html
+        /café                       crash ERR_INVALID_CHAR
+        //file                      301 /file → 200 file.html
+        /%E0%A4%A                   400 Bad Request
+        /..%2Fdocusaurus.config.js  400 Bad Request"
+      `);
+    });
+  });
+
+  describe('baseUrl /base/', () => {
+    it('trailingSlash undefined', async () => {
+      const result = await describeServing(
+        {baseUrl: '/base/', trailingSlash: undefined},
+        RequestPaths,
+      );
+      expect(result).toMatchInlineSnapshot(`
+        "/base/                           200 index.html
+        /base/index                      301 / → 302 /base/ → 200 index.html
+        /base/index.html                 301 /index → 302 /base/ → 200 index.html
+        /base/file                       200 file.html
+        /base/file/                      200 file.html
+        /base/file.html                  301 /file → 302 /base/ → 200 index.html
+        /base/folder                     200 folder/index.html
+        /base/folder/                    200 folder/index.html
+        /base/folder/index               301 /folder → 302 /base/ → 200 index.html
+        /base/folder/index.html          301 /folder/index → 302 /base/ → 200 index.html
+        /base/both                       200 both/index.html
+        /base/both/                      200 both/index.html
+        /base/both.html                  301 /both → 302 /base/ → 200 index.html
+        /base/both/index.html            301 /both/index → 302 /base/ → 200 index.html
+        /base/docs/2.x                   404 404.html
+        /base/docs/2.x/                  404 404.html
+        /base/assets/css/styles.css      200 assets/css/styles.css
+        /base/assets/css/styles.css?v=1  200 assets/css/styles.css
+        /base/assets/                    404 404.html
+        /base/assets/files/main.c        200 assets/files/main.c
+        /base/assets/files/document.pdf  200 assets/files/document.pdf
+        /base/assets/images/photo.jpeg   200 assets/images/photo.jpeg
+        /base/assets/fonts/font.woff2    200 assets/fonts/font.woff2
+        /base/site.webmanifest           200 site.webmanifest
+        /base/missing                    404 404.html
+        /base/missing/                   404 404.html
+        /base/missing.html               301 /missing → 302 /base/ → 200 index.html
+        /base/file?query=1               200 file.html
+        /base/file/?query=1              200 file.html
+        /base/file.html?query=1          301 /file → 302 /base/ → 200 index.html
+        /base/folder?query=1             200 folder/index.html
+        /base/with%20space               200 with space.html
+        /base/with%20space.html          301 /with%20space → 302 /base/ → 200 index.html
+        /base/файл                       200 файл.html
+        /base/файл.html                  301 /%D1%84%D0%B0%D0%B9%D0%BB → 302 /base/ → 200 index.html
+        /base/café                       crash ERR_INVALID_CHAR
+        /base//file                      200 file.html
+        /base/%E0%A4%A                   400 Bad Request
+        /base/..%2Fdocusaurus.config.js  400 Bad Request"
+      `);
+    });
+
+    // Windows serves file URLs with a trailing slash, other platforms 404
+    // TODO merge once looksLikeAsset is fixed and doesn't add one to files
+    it.skipIf(process.platform === 'win32')('trailingSlash true', async () => {
+      const result = await describeServing(
+        {baseUrl: '/base/', trailingSlash: true},
+        RequestPaths,
+      );
+      expect(result).toMatchInlineSnapshot(`
+        "/base/                           200 index.html
+        /base/index                      302 /base/index/ → 200 index.html
+        /base/index.html                 301 /index → 302 /base/ → 200 index.html
+        /base/file                       302 /base/file/ → 200 file.html
+        /base/file/                      200 file.html
+        /base/file.html                  301 /file → 302 /base/ → 200 index.html
+        /base/folder                     302 /base/folder/ → 200 folder/index.html
+        /base/folder/                    200 folder/index.html
+        /base/folder/index               302 /base/folder/index/ → 200 folder/index.html
+        /base/folder/index.html          301 /folder/index → 302 /base/ → 200 index.html
+        /base/both                       302 /base/both/ → 200 both/index.html
+        /base/both/                      200 both/index.html
+        /base/both.html                  301 /both → 302 /base/ → 200 index.html
+        /base/both/index.html            301 /both/index → 302 /base/ → 200 index.html
+        /base/docs/2.x                   404 404.html
+        /base/docs/2.x/                  404 404.html
+        /base/assets/css/styles.css      200 assets/css/styles.css
+        /base/assets/css/styles.css?v=1  302 /base/assets/css/styles.css/?v=1 → 404 404.html
+        /base/assets/                    404 404.html
+        /base/assets/files/main.c        200 assets/files/main.c
+        /base/assets/files/document.pdf  200 assets/files/document.pdf
+        /base/assets/images/photo.jpeg   200 assets/images/photo.jpeg
+        /base/assets/fonts/font.woff2    302 /base/assets/fonts/font.woff2/ → 404 404.html
+        /base/site.webmanifest           302 /base/site.webmanifest/ → 404 404.html
+        /base/missing                    302 /base/missing/ → 404 404.html
+        /base/missing/                   404 404.html
+        /base/missing.html               301 /missing → 302 /base/ → 200 index.html
+        /base/file?query=1               302 /base/file/?query=1 → 200 file.html
+        /base/file/?query=1              200 file.html
+        /base/file.html?query=1          302 /base/file.html/?query=1 → 404 404.html
+        /base/folder?query=1             302 /base/folder/?query=1 → 200 folder/index.html
+        /base/with%20space               302 /base/with%20space/ → 200 with space.html
+        /base/with%20space.html          301 /with%20space → 302 /base/ → 200 index.html
+        /base/файл                       302 /base/%D1%84%D0%B0%D0%B9%D0%BB/ → 200 файл.html
+        /base/файл.html                  301 /%D1%84%D0%B0%D0%B9%D0%BB → 302 /base/ → 200 index.html
+        /base/café                       302 /base/caf%C3%A9/ → crash ERR_INVALID_CHAR
+        /base//file                      302 /base//file/ → 301 /file/ → 302 /base/ → 200 index.html
+        /base/%E0%A4%A                   302 /base/%E0%A4%A/ → 400 Bad Request
+        /base/..%2Fdocusaurus.config.js  400 Bad Request"
+      `);
+    });
+
+    it.skipIf(process.platform !== 'win32')(
+      'trailingSlash true, on Windows',
+      async () => {
+        const result = await describeServing(
+          {baseUrl: '/base/', trailingSlash: true},
+          RequestPaths,
+        );
+        expect(result).toMatchInlineSnapshot(`
+          "/base/                           200 index.html
+          /base/index                      302 /base/index/ → 200 index.html
+          /base/index.html                 301 /index → 302 /base/ → 200 index.html
+          /base/file                       302 /base/file/ → 200 file.html
+          /base/file/                      200 file.html
+          /base/file.html                  301 /file → 302 /base/ → 200 index.html
+          /base/folder                     302 /base/folder/ → 200 folder/index.html
+          /base/folder/                    200 folder/index.html
+          /base/folder/index               302 /base/folder/index/ → 200 folder/index.html
+          /base/folder/index.html          301 /folder/index → 302 /base/ → 200 index.html
+          /base/both                       302 /base/both/ → 200 both/index.html
+          /base/both/                      200 both/index.html
+          /base/both.html                  301 /both → 302 /base/ → 200 index.html
+          /base/both/index.html            301 /both/index → 302 /base/ → 200 index.html
+          /base/docs/2.x                   404 404.html
+          /base/docs/2.x/                  404 404.html
+          /base/assets/css/styles.css      200 assets/css/styles.css
+          /base/assets/css/styles.css?v=1  302 /base/assets/css/styles.css/?v=1 → 200 assets/css/styles.css
+          /base/assets/                    404 404.html
+          /base/assets/files/main.c        200 assets/files/main.c
+          /base/assets/files/document.pdf  200 assets/files/document.pdf
+          /base/assets/images/photo.jpeg   200 assets/images/photo.jpeg
+          /base/assets/fonts/font.woff2    302 /base/assets/fonts/font.woff2/ → 200 assets/fonts/font.woff2
+          /base/site.webmanifest           302 /base/site.webmanifest/ → 200 site.webmanifest
+          /base/missing                    302 /base/missing/ → 404 404.html
+          /base/missing/                   404 404.html
+          /base/missing.html               301 /missing → 302 /base/ → 200 index.html
+          /base/file?query=1               302 /base/file/?query=1 → 200 file.html
+          /base/file/?query=1              200 file.html
+          /base/file.html?query=1          302 /base/file.html/?query=1 → 200 file.html
+          /base/folder?query=1             302 /base/folder/?query=1 → 200 folder/index.html
+          /base/with%20space               302 /base/with%20space/ → 200 with space.html
+          /base/with%20space.html          301 /with%20space → 302 /base/ → 200 index.html
+          /base/файл                       302 /base/%D1%84%D0%B0%D0%B9%D0%BB/ → 200 файл.html
+          /base/файл.html                  301 /%D1%84%D0%B0%D0%B9%D0%BB → 302 /base/ → 200 index.html
+          /base/café                       302 /base/caf%C3%A9/ → crash ERR_INVALID_CHAR
+          /base//file                      302 /base//file/ → 301 /file/ → 302 /base/ → 200 index.html
+          /base/%E0%A4%A                   302 /base/%E0%A4%A/ → 400 Bad Request
+          /base/..%2Fdocusaurus.config.js  400 Bad Request"
+        `);
+      },
+    );
+
+    it('trailingSlash false', async () => {
+      const result = await describeServing(
+        {baseUrl: '/base/', trailingSlash: false},
+        RequestPaths,
+      );
+      expect(result).toMatchInlineSnapshot(`
+        "/base/                           200 index.html
+        /base/index                      301 / → 302 /base/ → 200 index.html
+        /base/index.html                 301 /index → 302 /base/ → 200 index.html
+        /base/file                       200 file.html
+        /base/file/                      302 /base/file → 200 file.html
+        /base/file.html                  301 /file → 302 /base/ → 200 index.html
+        /base/folder                     200 folder/index.html
+        /base/folder/                    302 /base/folder → 200 folder/index.html
+        /base/folder/index               301 /folder → 302 /base/ → 200 index.html
+        /base/folder/index.html          301 /folder/index → 302 /base/ → 200 index.html
+        /base/both                       200 both/index.html
+        /base/both/                      302 /base/both → 200 both/index.html
+        /base/both.html                  301 /both → 302 /base/ → 200 index.html
+        /base/both/index.html            301 /both/index → 302 /base/ → 200 index.html
+        /base/docs/2.x                   404 404.html
+        /base/docs/2.x/                  302 /base/docs/2.x → 404 404.html
+        /base/assets/css/styles.css      200 assets/css/styles.css
+        /base/assets/css/styles.css?v=1  200 assets/css/styles.css
+        /base/assets/                    302 /base/assets → 404 404.html
+        /base/assets/files/main.c        200 assets/files/main.c
+        /base/assets/files/document.pdf  200 assets/files/document.pdf
+        /base/assets/images/photo.jpeg   200 assets/images/photo.jpeg
+        /base/assets/fonts/font.woff2    200 assets/fonts/font.woff2
+        /base/site.webmanifest           200 site.webmanifest
+        /base/missing                    404 404.html
+        /base/missing/                   302 /base/missing → 404 404.html
+        /base/missing.html               301 /missing → 302 /base/ → 200 index.html
+        /base/file?query=1               200 file.html
+        /base/file/?query=1              302 /base/file?query=1 → 200 file.html
+        /base/file.html?query=1          301 /file → 302 /base/ → 200 index.html
+        /base/folder?query=1             200 folder/index.html
+        /base/with%20space               200 with space.html
+        /base/with%20space.html          301 /with%20space → 302 /base/ → 200 index.html
+        /base/файл                       200 файл.html
+        /base/файл.html                  301 /%D1%84%D0%B0%D0%B9%D0%BB → 302 /base/ → 200 index.html
+        /base/café                       crash ERR_INVALID_CHAR
+        /base//file                      301 /file → 302 /base/ → 200 index.html
+        /base/%E0%A4%A                   400 Bad Request
+        /base/..%2Fdocusaurus.config.js  400 Bad Request"
+      `);
+    });
+
+    it('redirects requests outside the baseUrl', async () => {
+      const result = await describeRequests(
+        {baseUrl: '/base/', trailingSlash: undefined},
+        ['/', '/file', '/base', '/base?query=1', '/basement'],
+      );
+      expect(result).toMatchInlineSnapshot(`
+        "/              302 /base/ → 200 index.html
+        /file          302 /base/ → 200 index.html
+        /base          302 /base/ → 200 index.html
+        /base?query=1  302 /base/ → 200 index.html
+        /basement      302 /base/ → 200 index.html"
+      `);
+    });
+  });
+
+  // These tests capture the buggy behavior, also visible in the snapshots above
+  describe('known bugs', () => {
+    // TODO fix: serve café.html instead of crashing the server process
+    // See https://github.com/vercel/serve-handler/issues/205
+    it('crashes on file names with Latin-1 characters', async () => {
+      await expect(
+        serveRequest({baseUrl: '/', trailingSlash: undefined}, '/café'),
+      ).resolves.toBe('crash ERR_INVALID_CHAR');
+    });
+
+    // TODO fix: keep the baseUrl, "301 /base/file → 200 file.html"
+    // See https://github.com/meta/docusaurus/issues/10078#issuecomment-2084932934
+    it('drops the baseUrl in serve-handler redirects', async () => {
+      await expect(
+        serveRequest(
+          {baseUrl: '/base/', trailingSlash: undefined},
+          '/base/file.html',
+        ),
+      ).resolves.toBe('301 /file → 302 /base/ → 200 index.html');
+    });
+
+    // TODO fix: keep the query string, "301 /file?query=1 → 200 file.html"
+    it('drops the query string in serve-handler redirects', async () => {
+      await expect(
+        serveRequest(
+          {baseUrl: '/', trailingSlash: undefined},
+          '/file.html?query=1',
+        ),
+      ).resolves.toBe('301 /file → 200 file.html');
+    });
+
+    // TODO fix: serve docs/2.x/index.html, like the index.html of any folder
+    // serve-handler doesn't look for it when the path has an extension (.x)
+    it('does not serve folders with a dot in their name', async () => {
+      await expect(
+        serveRequest({baseUrl: '/', trailingSlash: undefined}, '/docs/2.x/'),
+      ).resolves.toBe('404 404.html');
+    });
+
+    // TODO fix: serve these assets without adding a trailing slash
+    // The looksLikeAsset regex misses them
+    // See https://github.com/meta/docusaurus/pull/10090
+    // Windows serves file URLs with a trailing slash, other platforms 404
+    describe('adds a trailing slash to some assets under a baseUrl', () => {
+      const options: ServeOptions = {baseUrl: '/base/', trailingSlash: true};
+
+      it.skipIf(process.platform === 'win32')(
+        'with a query string',
+        async () => {
+          await expect(
+            serveRequest(options, '/base/assets/css/styles.css?v=1'),
+          ).resolves.toBe(
+            '302 /base/assets/css/styles.css/?v=1 → 404 404.html',
+          );
+        },
+      );
+
+      it.skipIf(process.platform !== 'win32')(
+        'with a query string, on Windows',
+        async () => {
+          await expect(
+            serveRequest(options, '/base/assets/css/styles.css?v=1'),
+          ).resolves.toBe(
+            '302 /base/assets/css/styles.css/?v=1 → 200 assets/css/styles.css',
+          );
+        },
+      );
+
+      it.skipIf(process.platform === 'win32')(
+        'with an extension longer than 4 characters',
+        async () => {
+          await expect(
+            serveRequest(options, '/base/assets/fonts/font.woff2'),
+          ).resolves.toBe('302 /base/assets/fonts/font.woff2/ → 404 404.html');
+          await expect(
+            serveRequest(options, '/base/site.webmanifest'),
+          ).resolves.toBe('302 /base/site.webmanifest/ → 404 404.html');
+        },
+      );
+
+      it.skipIf(process.platform !== 'win32')(
+        'with an extension longer than 4 characters, on Windows',
+        async () => {
+          await expect(
+            serveRequest(options, '/base/assets/fonts/font.woff2'),
+          ).resolves.toBe(
+            '302 /base/assets/fonts/font.woff2/ → 200 assets/fonts/font.woff2',
+          );
+          await expect(
+            serveRequest(options, '/base/site.webmanifest'),
+          ).resolves.toBe('302 /base/site.webmanifest/ → 200 site.webmanifest');
+        },
+      );
+    });
+  });
+});
diff --git a/packages/docusaurus/src/commands/serve/__tests__/testUtils.ts b/packages/docusaurus/src/commands/serve/__tests__/testUtils.ts
new file mode 100644
index 000000000000..523c9f973791
--- /dev/null
+++ b/packages/docusaurus/src/commands/serve/__tests__/testUtils.ts
@@ -0,0 +1,151 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import http from 'node:http';
+import path from 'node:path';
+import {pathExists} from '@docusaurus/fs';
+import {listenToServer} from '../listenToServer';
+import {createServeRequestHandler} from '../requestHandler';
+import type {AddressInfo} from 'node:net';
+import type {DocusaurusConfig} from '@docusaurus/types';
+
+export type ServeOptions = Pick<DocusaurusConfig, 'baseUrl' | 'trailingSlash'>;
+
+const fixtureOutDir = path.join(__dirname, '__fixtures__/build');
+
+// Added by the test server when the request handler rejects
+const CrashHeader = 'x-test-crash';
+
+const MaxRedirects = 5;
+
+// The request paths are appended to the baseUrl
+export async function describeServing(
+  options: ServeOptions,
+  requestPaths: string[],
+): Promise<string> {
+  const baseUrlPrefix = options.baseUrl.replace(/\/$/, '');
+  const paths = requestPaths.map((requestPath) => baseUrlPrefix + requestPath);
+  return describeRequests(options, paths);
+}
+
+// One line per request, aligned to be easy to review in snapshots
+export async function describeRequests(
+  options: ServeOptions,
+  paths: string[],
+): Promise<string> {
+  const descriptions = await withServer(options, (origin) =>
+    Promise.all(
+      paths.map((requestPath) => describeRequest(origin, requestPath)),
+    ),
+  );
+  const pathWidth = Math.max(...paths.map((requestPath) => requestPath.length));
+  return paths
+    .map(
+      (requestPath, index) =>
+        `${requestPath.padEnd(pathWidth)}  ${descriptions[index]}`,
+    )
+    .join('\n');
+}
+
+export async function serveRequest(
+  options: ServeOptions,
+  requestPath: string,
+): Promise<string> {
+  return withServer(options, (origin) => describeRequest(origin, requestPath));
+}
+
+async function withServer<T>(
+  options: ServeOptions,
+  callback: (origin: string) => Promise<T>,
+): Promise<T> {
+  const handleRequest = createServeRequestHandler({
+    outDir: fixtureOutDir,
+    ...options,
+  });
+  const server = http.createServer((req, res) => {
+    handleRequest(req, res).catch((error: NodeJS.ErrnoException) =>
+      respondWithCrash(res, error),
+    );
+  });
+
+  await listenToServer({server, host: '127.0.0.1', port: 0});
+  try {
+    const {port} = server.address() as AddressInfo;
+    return await callback(`http://127.0.0.1:${port}`);
+  } finally {
+    server.closeAllConnections();
+    server.close();
+  }
+}
+
+// In production, this rejection is unhandled and crashes the server process
+function respondWithCrash(
+  res: http.ServerResponse,
+  error: NodeJS.ErrnoException,
+) {
+  if (res.headersSent) {
+    res.destroy();
+    return;
+  }
+  // A failed writeHead() can leave the Content-Length of the file to serve
+  res.writeHead(500, {
+    [CrashHeader]: error.code ?? 'unknown',
+    'Content-Length': 0,
+  });
+  res.end();
+}
+
+/**
+ * Requests a path and follows its redirects, to describe how it's served:
+ * "301 /file → 200 file.html"
+ */
+async function describeRequest(
+  origin: string,
+  requestPath: string,
+): Promise<string> {
+  const descriptions: string[] = [];
+
+  // Concatenated: new URL('//file', origin) would read "file" as a host name
+  let url = origin + requestPath;
+  while (descriptions.length <= MaxRedirects) {
+    const response = await fetch(url, {redirect: 'manual'});
+    descriptions.push(await describeResponse(response));
+
+    const location = response.headers.get('location');
+    if (location === null) {
+      break;
+    }
+    url = new URL(location, url).href;
+  }
+
+  return descriptions.join(' → ');
+}
+
+async function describeResponse(response: Response): Promise<string> {
+  const body = await response.text();
+
+  const crashCode = response.headers.get(CrashHeader);
+  if (crashCode !== null) {
+    return `crash ${crashCode}`;
+  }
+
+  const location = response.headers.get('location');
+  if (location !== null) {
+    return `${response.status} ${location}`;
+  }
+
+  const servedFile = (await getServedFixtureFile(body)) ?? response.statusText;
+  return `${response.status} ${servedFile}`;
+}
+
+// Each fixture build file contains its own path
+async function getServedFixtureFile(body: string): Promise<string | undefined> {
+  const filePath = body.trim();
+  const isFixtureFile =
+    filePath !== '' && (await pathExists(path.join(fixtureOutDir, filePath)));
+  return isFixtureFile ? filePath : undefined;
+}
diff --git a/project-words.txt b/project-words.txt
index e085dc646771..ddcd760b6159 100644
--- a/project-words.txt
+++ b/project-words.txt
@@ -352,3 +352,4 @@ zedspencermilnes
 Zhou
 zpao
 ödingers
+файл