Go Modules Cheat Sheet

Explains Go modules: initializing go.mod, adding and upgrading dependencies with go get, go mod tidy, and semantic versioning rules.

1 PageBeginnerApr 8, 2026

Initializing a Module

Creating go.mod and building the module.

bash

go mod init github.com/username/myproject   # Create go.mod, declares the module pathgo build ./...                              # Build all packages in the modulego run main.go                              # Compile and run

Managing Dependencies

Adding, upgrading, and cleaning up dependencies.

bash

go get github.com/gin-gonic/gin@v1.9.1   # Add a dependency at a specific versiongo get -u ./...                          # Upgrade all dependencies to latest minor/patchgo mod tidy                              # Add missing / remove unused dependenciesgo list -m all                           # List the module and all its dependencies

go.mod File

The declaration file for a module and its requirements.

yaml

module github.com/username/myprojectgo 1.22require (    github.com/gin-gonic/gin v1.9.1    github.com/stretchr/testify v1.8.4)require (    // indirect dependencies pulled in transitively    github.com/bytedance/sonic v1.9.1 // indirect)

Concepts

How Go's module system resolves and verifies dependencies.

go.mod- Declares the module path, Go version, and direct/indirect dependencies
go.sum- Records cryptographic checksums of dependencies to ensure reproducible, verified builds
Semantic versioning- Modules are versioned vX.Y.Z; major version 2+ requires a /vN suffix on the import path
Minimal version selection- Go picks the minimum version satisfying all module requirements, not always the latest
replace directive- replace old/module => ../local/path swaps a dependency for local development
go mod tidy- Reconciles go.mod/go.sum with what the code actually imports
GOPROXY- Environment variable controlling the module proxy used to fetch dependencies (default proxy.golang.org)

Pro Tip

Run go mod tidy before every commit that changes imports — it keeps go.mod and go.sum in sync and catches unused or missing dependencies that would otherwise fail a clean CI build.

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