Aider

Aider is the leading open-source AI pair programming tool, operating as a CLI that edits code directly in your local git repository. With over 22,000 GitHub stars, Aider has established itself as the go-to terminal-based coding assistant for developers who want powerful AI help without leaving their preferred editor and workflow.

Aider is deeply git-aware: it automatically commits each set of changes with descriptive messages, making it easy to review, diff, or revert AI-generated modifications. It supports all major LLM providers including OpenAI, Anthropic, Google, and local models via Ollama, with an innovative architect/editor dual-model pattern that uses a stronger model for planning and a faster one for implementation, optimizing both quality and cost.

The tool features multiple editing modes (whole file, diff, unified diff) optimized for different models, a map of your repository structure for intelligent context management, linting integration to catch errors before committing, and the ability to selectively add specific files to the conversation context. Aider consistently ranks at the top of coding benchmarks and maintains a public leaderboard comparing model performance on real coding tasks, making it a valuable resource for the broader AI coding community.

Aider's bring-your-own-key model means the tool itself is completely free, with costs limited to your API provider usage. Its active open-source community contributes features, bug fixes, and model support on a regular basis.