diff --git a/.github/workflows/font_tests.yml b/.github/workflows/font_tests.yml
new file mode 100644
index 0000000000000..34c06cbc6840c
--- /dev/null
+++ b/.github/workflows/font_tests.yml
@@ -0,0 +1,64 @@
+name: Font tests
+on:
+  push:
+    paths:
+      - 'gulpfile.mjs'
+      - 'src/**'
+      - 'test/test.mjs'
+      - 'test/font/**'
+      - '.github/workflows/font_tests.yml'
+    branches:
+      - master
+  pull_request:
+    paths:
+      - 'gulpfile.mjs'
+      - 'src/**'
+      - 'test/test.mjs'
+      - 'test/font/**'
+      - '.github/workflows/font_tests.yml'
+    branches:
+      - master
+  workflow_dispatch:
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: Test
+
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: [lts/*]
+        os: [windows-latest, ubuntu-latest]
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install Gulp
+        run: npm install -g gulp-cli
+
+      - name: Install other dependencies
+        run: npm install
+
+      - name: Use Python 3.12
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.12'
+          cache: 'pip'
+
+      - name: Install Fonttools
+        run: pip install fonttools
+
+      - name: Run font tests
+        run: gulp fonttest --headless
diff --git a/.gitmodules b/.gitmodules
deleted file mode 100644
index 2de02d7d1f3a9..0000000000000
--- a/.gitmodules
+++ /dev/null
@@ -1,3 +0,0 @@
-[submodule "test/ttx/fonttools-code"]
-	path = test/ttx/fonttools-code
-	url = https://github.com/behdad/fonttools.git
diff --git a/gulpfile.mjs b/gulpfile.mjs
index 43c66755a7190..7f17b707278bf 100644
--- a/gulpfile.mjs
+++ b/gulpfile.mjs
@@ -1749,7 +1749,6 @@ gulp.task(
     return streamqueue(
       { objectMode: true },
       createTestSource("unit", { bot: true }),
-      createTestSource("font", { bot: true }),
       createTestSource("browser", { bot: true }),
       createTestSource("integration")
     );
@@ -1774,7 +1773,6 @@ gulp.task(
     return streamqueue(
       { objectMode: true },
       createTestSource("unit", { bot: true }),
-      createTestSource("font", { bot: true }),
       createTestSource("browser", { bot: true, xfaOnly: true }),
       createTestSource("integration")
     );
diff --git a/test/font/README.md b/test/font/README.md
new file mode 100644
index 0000000000000..c3f31cc9e52f2
--- /dev/null
+++ b/test/font/README.md
@@ -0,0 +1,36 @@
+# Font tests
+
+The font tests check if PDF.js can read font data correctly. For validation
+the `ttx` tool (from the Python `fonttools` library) is used that can convert
+font data to an XML format that we can easily use for assertions in the tests.
+In the font tests we let PDF.js read font data and pass the PDF.js-interpreted
+font data through `ttx` to check its correctness. The font tests are successful
+if PDF.js can successfully read the font data and `ttx` can successfully read
+the PDF.js-interpreted font data back, proving that PDF.js does not apply any
+transformations that break the font data.
+
+## Running the font tests
+
+The font tests are run on GitHub Actions using the workflow defined in
+`.github/workflows/font_tests.yml`, but it is also possible to run the font
+tests locally. The current stable versions of the following dependencies are
+required to be installed on the system:
+
+- Python 3
+- `fonttools` (see https://pypi.org/project/fonttools and https://github.com/fonttools/fonttools)
+
+The recommended way of installing `fonttools` is using `pip` in a virtual
+environment because it avoids having to do a system-wide installation and
+therefore improves isolation, but any other way of installing `fonttools`
+that makes `ttx` available in the `PATH` environment variable also works.
+
+Using the virtual environment approach the font tests can be run locally by
+creating and sourcing a virtual environment with `fonttools` installed in
+it before running the font tests:
+    
+```
+python3 -m venv venv
+source venv/bin/activate
+pip install fonttools
+gulp fonttest
+```
diff --git a/test/font/ttxdriver.mjs b/test/font/ttxdriver.mjs
index cdfbf7d72e5dc..c820d8ccf6ac0 100644
--- a/test/font/ttxdriver.mjs
+++ b/test/font/ttxdriver.mjs
@@ -14,65 +14,43 @@
  * limitations under the License.
  */
 
-import { fileURLToPath } from "url";
 import fs from "fs";
+import os from "os";
 import path from "path";
 import { spawn } from "child_process";
 
-const __dirname = path.dirname(fileURLToPath(import.meta.url));
+let ttxTaskId = Date.now();
 
-const ttxResourcesHome = path.join(__dirname, "..", "ttx");
-
-let nextTTXTaskId = Date.now();
-
-function runTtx(ttxResourcesHomePath, fontPath, registerOnCancel, callback) {
-  fs.realpath(ttxResourcesHomePath, function (error, realTtxResourcesHomePath) {
-    const fontToolsHome = path.join(realTtxResourcesHomePath, "fonttools-code");
-    fs.realpath(fontPath, function (errorFontPath, realFontPath) {
-      const ttxPath = path.join("Lib", "fontTools", "ttx.py");
-      if (!fs.existsSync(path.join(fontToolsHome, ttxPath))) {
-        callback("TTX was not found, please checkout PDF.js submodules");
-        return;
-      }
-      const ttxEnv = {
-        PYTHONPATH: path.join(fontToolsHome, "Lib"),
-        PYTHONDONTWRITEBYTECODE: true,
-      };
-      const ttxStdioMode = "ignore";
-      const python = process.platform !== "win32" ? "python2" : "python";
-      const ttx = spawn(python, [ttxPath, realFontPath], {
-        cwd: fontToolsHome,
-        stdio: ttxStdioMode,
-        env: ttxEnv,
-      });
-      let ttxRunError;
-      registerOnCancel(function (reason) {
-        ttxRunError = reason;
-        callback(reason);
-        ttx.kill();
-      });
-      ttx.on("error", function (errorTtx) {
-        ttxRunError = errorTtx;
-        callback("Unable to execute ttx");
-      });
-      ttx.on("close", function (code) {
-        if (ttxRunError) {
-          return;
-        }
-        callback();
-      });
-    });
+function runTtx(fontPath, registerOnCancel, callback) {
+  const ttx = spawn("ttx", [fontPath], { stdio: "ignore" });
+  let ttxRunError;
+  registerOnCancel(function (reason) {
+    ttxRunError = reason;
+    callback(reason);
+    ttx.kill();
+  });
+  ttx.on("error", function (errorTtx) {
+    ttxRunError = errorTtx;
+    callback(
+      "Unable to execute `ttx`; make sure the `fonttools` dependency is installed"
+    );
+  });
+  ttx.on("close", function (code) {
+    if (ttxRunError) {
+      return;
+    }
+    callback();
   });
 }
 
 function translateFont(content, registerOnCancel, callback) {
   const buffer = Buffer.from(content, "base64");
-  const taskId = (nextTTXTaskId++).toString();
-  const fontPath = path.join(ttxResourcesHome, taskId + ".otf");
-  const resultPath = path.join(ttxResourcesHome, taskId + ".ttx");
+  const taskId = (ttxTaskId++).toString();
+  const fontPath = path.join(os.tmpdir(), `pdfjs-font-test-${taskId}.otf`);
+  const resultPath = path.join(os.tmpdir(), `pdfjs-font-test-${taskId}.ttx`);
 
   fs.writeFileSync(fontPath, buffer);
-  runTtx(ttxResourcesHome, fontPath, registerOnCancel, function (err) {
+  runTtx(fontPath, registerOnCancel, function (err) {
     fs.unlinkSync(fontPath);
     if (err) {
       console.error(err);
diff --git a/test/ttx/README.md b/test/ttx/README.md
deleted file mode 100644
index 98bfd86921a14..0000000000000
--- a/test/ttx/README.md
+++ /dev/null
@@ -1 +0,0 @@
-If `git clone --recursive` was not used, please run `git submodule init; git submodule update` to pull fonttools code.
diff --git a/test/ttx/fonttools-code b/test/ttx/fonttools-code
deleted file mode 160000
index d8170131a3458..0000000000000
--- a/test/ttx/fonttools-code
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit d8170131a3458ffbc19089cf33249777bde390e7