diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
new file mode 100644
index 0000000..57f8d63
--- /dev/null
+++ b/.github/workflows/codeql.yml
@@ -0,0 +1,46 @@
+name: CodeQL
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    - cron: '30 1 * * 1'
+
+permissions:
+  contents: read
+
+jobs:
+  analyze:
+    name: Analyze (${{ matrix.language }})
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      packages: read
+      security-events: write
+    strategy:
+      fail-fast: false
+      matrix:
+        # The site has no Python source, so `python` is deliberately absent:
+        # CodeQL fails with "could not process any code written in Python" when
+        # a language in the matrix has no files. Add it back with a `.py` file.
+        include:
+          - language: actions
+            build-mode: none
+          - language: javascript-typescript
+            build-mode: none
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v4
+        with:
+          languages: ${{ matrix.language }}
+          build-mode: ${{ matrix.build-mode }}
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v4
+        with:
+          category: /language:${{ matrix.language }}