diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..0734bdd
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,26 @@
+name: CI
+
+# Every pull request, e.g. a bump of glpython-editor: tsc catches type changes
+# in a new editor tag before the merge deploys the IDE.
+on:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+      # As in deploy-pages.yml: glpython-editor is installed from git.
+      - name: Use HTTPS for git dependencies
+        run: git config --global url."https://github.com/".insteadOf "ssh://git@github.com/"
+      - run: npm ci
+      # tsc -b && vite build
+      - run: npm run build
+      - run: npm run lint