diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..da2e946
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,37 @@
+name: ci
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    name: test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.22'
+          cache: true
+      - name: vet
+        run: go vet ./...
+      - name: build
+        run: go build ./...
+      - name: test
+        run: go test -race -count=1 ./...
+
+  lint:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.22'
+          cache: true
+      - uses: golangci/golangci-lint-action@v6
+        with:
+          version: latest
diff --git a/.gitignore b/.gitignore
index b89be2e..11d5f5b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,10 @@
 *.test
 *.out
 
+# coverage
+coverage.out
+coverage.html
+
 # go
 /vendor/
 
@@ -13,4 +17,7 @@
 *.swp
 
 # os
-.DS_Store
+**/.DS_Store
+
+# user backups created during testing
+*.bak*-*
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..745270f
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Lukasz Raczylo
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/Makefile b/Makefile
index f21f99d..4680b3a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: build test lint clean install
+.PHONY: build test lint test-race cover tidy clean install
 
 BIN := harness-sync
 VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo dev)
@@ -11,7 +11,19 @@ test:
 	go test ./...
 
 lint:
-	go vet ./...
+	golangci-lint run ./...
+
+test-race:
+	go test -race -count=1 ./...
+
+cover:
+	go test -coverprofile=coverage.out ./...
+	go tool cover -html=coverage.out -o coverage.html
+	@echo "open coverage.html"
+
+tidy:
+	go mod tidy
+	gofmt -s -w .
 
 install: build
 	install -m 0755 $(BIN) $$HOME/.local/bin/$(BIN)