You clone a new repo. What’s the command to run tests? Build the project? Deploy? Every project is different—until you add a justfile.

What is just?

just is a command runner with over 30,000 GitHub stars. It gives every project the same interface: just test, just build, just deploy. It works across languages, loads environment variables automatically, and runs on any platform. Think of it as a modern alternative to make, without the baggage.

Why use it?

Self-documenting. Type just to see all available commands with descriptions. New contributors are productive immediately.

Language-agnostic. Python, JavaScript, Rust, Swift—doesn’t matter. One tool for every project in your workflow.

Environment-aware. Automatically loads .env files. No more forgetting to source variables before running commands.

Cross-platform. Write recipes once, run them on macOS, Linux, and Windows without modification.

AI-friendly. AI coding assistants can run just check and just test consistently across all your projects without parsing build files or guessing commands.

Quick example

Create a justfile in your project root:

# Run tests
test:
    pytest tests/

# Format and lint
check:
    black .
    ruff check .

# Run development server
dev:
    python manage.py runserver

Now type just to see your commands, or just test to run them.

Conclusion

A justfile creates consistency across projects and removes cognitive overhead. Setup takes minutes. The productivity gains compound over time.