Aider
The AI pair-programmer on the command line, open source, that auto-commits your changes to Git
Overview
Aider is an open-source AI pair-programming tool running in your terminal. It maps your entire repository to understand context, lets you edit multiple files with a single prompt, and automatically creates clean Git commits for each change. It supports 100+ languages and works with Claude, GPT-4o, DeepSeek or local models via LM Studio, your choice.
Aider itself is entirely free and open source (Apache 2.0 licence). The only real cost comes from the LLM API: expect $10-30/month for moderate use with Claude Sonnet or GPT-4o, or nearly zero with economical DeepSeek models. Aider is reserved for developers comfortable with the terminal; there is no GUI or SaaS version.
Our verdict
Recommended for experienced developers wanting powerful code agents without monthly subscriptions and without shipping code to a proprietary platform: Aider is the best open-source tool in its category. Avoid if you are starting out or prefer a GUI; Cursor or Replit will be more accessible.