Aider

Aider is an open-source terminal pair programmer that edits code in your local git repository. It connects to multiple LLMs, understands project context, and can make multi-file edits while preserving git history. With 45,000+ GitHub stars, it is one of the most popular open-source coding agents.

Top features

• Multi-file editing: Aider can modify several files in a single turn, keeping changes coherent across the codebase.
• Git-aware workflow: every change is committed with a descriptive message, so the history stays clean and reversible.
• Universal LLM support: works with OpenAI, Anthropic, Google Gemini, local models via Ollama, and any OpenAI-compatible API.
• Repository context: reads the existing codebase to understand imports, types, and patterns before proposing edits.
• Voice coding: speak natural-language requests and Aider transcribes and executes them.
• Test-driven development: can run tests, read failures, and iterate on fixes automatically.
• Code map: builds a map of the repository structure to improve context understanding for large projects.

Use cases

• Add a feature that touches multiple files: model, controller, view, and tests.
• Refactor a module while preserving behavior and updating all call sites.
• Fix bugs by reading error traces, locating the source, and patching across the stack.
• Update dependencies and migrate APIs across the entire codebase.
• Work offline with local models for air-gapped or privacy-sensitive environments.