diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
new file mode 100644
index 0000000..60ab883
--- /dev/null
+++ b/.github/workflows/coverage.yml
@@ -0,0 +1,52 @@
+name: Coverage
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - 'v*'
+
+permissions:
+  contents: read
+
+concurrency:
+  group: coverage-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  coverage:
+    name: Coverage
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - name: Install mise
+        uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
+
+      - name: Cache Go modules and build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: go-${{ runner.os }}-${{ hashFiles('**/go.sum') }}
+          restore-keys: go-${{ runner.os }}-
+
+      - name: Download Go dependencies
+        run: go mod download
+
+      - name: Run tests with coverage
+        run: make cover
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          files: coverage.out
+          fail_ci_if_error: true
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
diff --git a/.gitignore b/.gitignore
index 3f90277..9b62ff9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,10 @@
 go.work
 go.work.sum
 
+# coverage output
+coverage.out
+coverage.html
+
 # Local configuration files
 *.local.*
 *.local/
diff --git a/Makefile b/Makefile
index d7d3ae0..779e053 100644
--- a/Makefile
+++ b/Makefile
@@ -14,6 +14,15 @@ lint:
 test:
 	go test -race -failfast ./...
 
+.PHONY: cover
+cover:
+	go test -race -covermode=atomic -coverprofile=coverage.out ./...
+	go tool cover -func=coverage.out
+
+.PHONY: cover-html
+cover-html: cover
+	go tool cover -html=coverage.out -o coverage.html
+
 .PHONY: check-tidy
 check-tidy:
 	go mod tidy -diff
diff --git a/README.md b/README.md
index d742551..36affe6 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # Generic Sync Map
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/min0625/gsyncmap.svg)](https://pkg.go.dev/github.com/min0625/gsyncmap)
+[![codecov](https://codecov.io/gh/min0625/gsyncmap/branch/main/graph/badge.svg)](https://codecov.io/gh/min0625/gsyncmap)
 
 **English** | [繁體中文](./README.zh-TW.md)
 
diff --git a/README.zh-TW.md b/README.zh-TW.md
index bdd2e86..d65c8d7 100644
--- a/README.zh-TW.md
+++ b/README.zh-TW.md
@@ -1,6 +1,7 @@
 # Generic Sync Map
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/min0625/gsyncmap.svg)](https://pkg.go.dev/github.com/min0625/gsyncmap)
+[![codecov](https://codecov.io/gh/min0625/gsyncmap/branch/main/graph/badge.svg)](https://codecov.io/gh/min0625/gsyncmap)
 
 [English](./README.md) | **繁體中文**