Aider is an open-source terminal tool that pairs Claude with your codebase for interactive development. You run aider with a list of files, describe the changes you want, and Claude modifies the code in real-time. You see diffs, approve/reject each change, and ask Claude to refine. Aider handles git commits automatically so you have a clean audit trail. Unlike IDEs (Cursor, Windsurf) or extensions (GitHub Copilot), Aider is terminal-native and editor-agnostic. You keep using your preferred editor (VSCode, Vim, Emacs) and Aider handles the AI pair programming layer. Aider prioritizes transparency—you always see what Claude is about to change before it commits.