Aider: AI pair programming in your terminal

How it works: a pair programmer that writes to your files

Created in 2023 by Paul Gauthier, Aider was one of the first command-line agentic coding tools. You launch it in a project folder, add the files to change to the chat, then describe what you want in plain English. Aider proposes the edits, applies them directly and creates a Git commit with a clear message, so you can use regular Git tools to diff or undo.

To cope with large projects, Aider builds a “map” of the repository (functions, classes, links between files) and sends it to the model, which helps it understand the codebase without overflowing the context window. It handles most popular languages: Python, JavaScript, Rust, Go, PHP, HTML and many more.

What else it can do

Aider can run your linters and tests after each change and fix the problems they report. It accepts images and web pages as context, voice input, and a copy-paste mode for working with a chatbot’s web interface instead of an API. It does not officially support the MCP protocol.

Getting started

Install the aider-install helper with pip, run it, move into your project and start aider with your chosen model and API key. Begin with a small task (adding a test, renaming a function) and review each commit before going further.

Strengths and limitations

Strengths: lightweight, editor-independent, free choice of model, excellent Git integration, Apache 2.0 license.

Limitations: text-only interface; it’s an assistant that moves step by step with you, not an autonomous agent that works for hours; the release pace has slowed noticeably since 2025. Costs depend entirely on the model you pick: estimate them with the agent cost calculator.

Alternatives

OpenHands delegates longer tasks to agents, goose offers a desktop app, and GitHub Copilot or Cursor build AI straight into the editor.