Aider

Aider is a terminal-based AI pair programming tool for developers who want to build, refactor, and fix code inside existing Git repositories using large language models.

• Repository-aware editing: builds a codebase map (via tree-sitter) to provide full-project context and support multi-file changes across 100+ languages (Python, JavaScript, Rust, Go, C/C++, and more).
• Git-first workflow: creates atomic commits with descriptive messages and supports reviewable changes with diffs and rollback (including /diff and /undo), making AI edits easier to inspect and reverse.
• Flexible model connections: works with cloud LLMs such as Claude 3.7 Sonnet, DeepSeek, and OpenAI models (o1, GPT-4o), plus local models; can also use browser copy/paste workflows when needed.
• Developer controls and automation: includes slash commands (for example /add, /drop, model switching, and /tokens), can run linting and tests and help fix failures, and supports voice-to-code plus adding images and web pages for extra context.

Pricing: Free (open-source); usage costs depend on the chosen LLM provider.

Notable for keeping the AI workflow close to the code and version control, with changes that stay auditable and undoable inside Git, plus adoption signals including 42K GitHub stars and 5.7M installs.