Aider

Aider is an open-source command line tool that lets you chat with a language model about the code in your Git repository. You ask for a change, and Aider edits the files directly and makes a commit with a sensible message, so every step is easy to review or undo. It builds a map of your repository to give the model useful context, and it works with many models, including Claude, GPT and local ones. Many people like it because it stays simple and transparent instead of hiding what it does. Aider itself is free. You pay only for the model API you connect, which keeps it popular with developers who want control over cost and tools.