Aider

An open-source AI pair programming tool that runs in your terminal. Aider edits files in your project using LLMs (Claude, GPT, local models). Git-integrated — each change is a commit. Free, supports any LLM, and works with your existing tools.

Created by

Paul Gauthier · Created Aider in 2023

Website

When to use

When you want a free, open-source AI coding tool.
Terminal-based workflows.
When you want to choose your LLM.
Git-native workflows.

When not to

When you want IDE integration (use Cursor).
When you need a polished UX.
When you can't manage your own LLM API keys.

Definition

Aider is an open-source terminal AI coding tool. It reads your codebase, edits files using LLMs, and commits changes to git. Supports many models (Claude, GPT, DeepSeek, local via Ollama). Voice mode, map mode (codebase understanding), and watch mode.

Why it exists

Cursor and Claude Code are proprietary and expensive. Aider is free, open-source, model-agnostic (use any LLM), and git-native — an alternative for developers who want control.

How it works

pip install aider-chat. Run aider in your project. It reads files, understands context, and edits code using your chosen LLM. Changes are git commits. /add, /drop, /commit commands. Works with Claude, GPT, or local models.

Scaling limits

Terminal-only (no IDE integration). Less polished than Cursor/Claude Code. Model quality varies (local models are worse). No built-in codebase indexing (reads files on demand).

Cost shape

Free and open source. You pay for the LLM API (or use free local models via Ollama).

Alternatives

Claude Code — More polished, Anthropic-only, paid.
Cursor — IDE-based, more features, paid.
Copilot — Autocomplete only, less agentic.

Failure modes

Terminal-only.
Less polished.
Model quality varies.
No built-in indexing.

Claude Code, Cursor, LLM (Large Language Model), AI agent, Ollama