Aider

Aider is an open-source AI pair programmer that edits code in your terminal and commits every change to git automatically.

Overview

Aider is a free, open-source command-line coding assistant that works directly against your local git repository. You describe a change in plain English, and Aider modifies the relevant files, shows a diff, and creates a sensible git commit with an auto-generated message. Because it is model-agnostic, you can pair it with Claude, GPT-class models, or local models served through Ollama and other providers. Its repository map helps the model understand large projects without loading everything into context.

Aider was one of the first open-source coding agents to gain mainstream adoption, and its design philosophy remains focused on transparency and developer control. Every edit is presented as a diff and recorded as a git commit, so the history of AI involvement is auditable and reversible. This makes it a comfortable choice for teams experimenting with AI assistance on production codebases.

The tool also shines in constrained environments: because it can drive local models through Ollama or llama.cpp, organizations with strict data policies can keep proprietary code entirely offline while still benefiting from agentic editing.

Key Features

• Git-aware editing with automatic commits, clean diffs, and undo via git history
• Repository map that summarizes your codebase so large projects stay in context
• Model flexibility: cloud APIs, local models, and custom OpenAI-compatible endpoints
• Multi-file refactors, test generation, and bug fixing from a single prompt
• Voice coding, linting integration, and editor integration via terminal or web UI
• Runs fully locally; source code can stay on your machine when you use local models

Pricing

Aider itself is completely free and open source under the Apache license. Your only cost is whatever you pay the model provider for API tokens, or nothing at all if you run local models.

Who Is It For

Developers who prefer the terminal, care about open-source tooling, or need privacy-friendly coding help with local models. It is especially popular with solo engineers and OSS maintainers who want AI edits without a subscription IDE.

FAQ

Is Aider free to use?

Yes. Aider is free and open source; you only pay for model API usage if you connect a paid model provider.

Does Aider offer an API?

Aider is a CLI and Python tool rather than a hosted service, but it can be scripted and embedded in automation pipelines, and it talks to any OpenAI-compatible model endpoint.

How does Aider compare to alternatives?

Unlike subscription AI IDEs, Aider stays in your terminal and keeps you in control of git history; against other CLI agents, its strengths are model freedom and lightweight setup.