Aider is an open-source AI pair programmer that runs in the terminal and allows developers to edit code in local git repositories using natural language. Unlike cloud IDEs, Aider works directly with your existing codebase in any editor — making multi-file edits, explaining code, writing tests, and committing changes via git. It supports all major LLMs including Claude, GPT-4, and locally running models, giving developers a privacy-preserving option for AI-assisted development that integrates into any existing workflow without forcing a change in development environment.