diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 940b6ac..a7851b1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,6 +9,7 @@ on:
       - main
   merge_group:
     types: [checks_requested]
+  workflow_dispatch: {}
 
 env:
   CARGO_TERM_COLOR: always
diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
new file mode 100644
index 0000000..cf19d31
--- /dev/null
+++ b/.github/workflows/coverage.yml
@@ -0,0 +1,34 @@
+name: Coverage check
+
+on:
+  push:
+    branches:
+      - main 
+  workflow_dispatch: {}
+
+jobs:
+  coverage:
+    runs-on: ${{ matrix.os }}-latest
+    strategy:
+      matrix:
+        os: [ubuntu]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: mozilla-actions/sccache-action@v0.0.3
+      - uses: dtolnay/rust-toolchain@nightly
+        with:
+          components: llvm-tools-preview
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Run tests with coverage instrumentation
+        run: |
+            cargo llvm-cov clean --workspace
+            cargo llvm-cov --doctests
+      - name: Generate coverage report
+        run: cargo llvm-cov report --codecov --output-path coverage.json
+      - name: Upload coverage to codecov.io
+        uses: codecov/codecov-action@v3
+        with:
+          files: coverage.json
+          name: ${{ matrix.os }}
+          token: ${{ secrets.CODECOV_TOKEN }}
diff --git a/README.md b/README.md
index 8ae909d..d5a3750 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,7 @@ portgraph
 [![build_status][]](https://github.com/CQCL/portgraph/actions)
 [![crates][]](https://crates.io/crates/portgraph)
 [![msrv][]](https://github.com/CQCL/portgraph)
+[![codecov][]](https://codecov.io/gh/CQCL/portgraph)
 
 Data structure library for directed graphs with first-level ports. Includes
 secondary data structures for node and port weights, and node hierarchies.
@@ -35,4 +36,5 @@ This project is licensed under Apache License, Version 2.0 ([LICENSE][] or http:
   [crates]: https://img.shields.io/crates/v/portgraph
   [LICENSE]: LICENCE
   [msrv]: https://img.shields.io/badge/rust-1.70.0%2B-blue.svg?maxAge=3600
+  [codecov]: https://img.shields.io/codecov/c/gh/CQCL/portgraph?logo=codecov
   [CHANGELOG]: CHANGELOG.md
\ No newline at end of file