Aider

Aider is an open-source command-line tool that lets you pair program with an LLM directly inside your local git repository. You chat in plain English about what you want changed, and Aider edits the relevant files, applies the diffs, and commits the result with a sensible message. It supports most major models, including GPT-4o, Claude, and various open-weight models through providers like Ollama, and it builds a map of your codebase using ctags so it can work intelligently across large multi-file projects rather than just the file you have open.

It's aimed at developers who want an AI coding assistant without leaving the terminal or switching to a cloud-based IDE. Typical use is adding a feature, fixing a bug, or refactoring a chunk of code by describing the change and letting Aider propose and apply the diff, run tests, and handle the commit, all while keeping the full history in git so every AI-made change is inspectable and revertible. It also supports voice input and can pull in image or web content as context for a request.

What sets it apart from many AI coding tools is how tightly it integrates with git and how model-agnostic it is: you're not locked into one vendor's assistant, and every change lands as a normal commit you can diff, squash, or roll back like any other. That git-native workflow, combined with being free and open source, has made it a favorite among developers who want full control over their codebase and history rather than delegating that to a hosted IDE.