Aider
Open-source command-line AI coding partner that edits code directly in your local git repo. Bring your own API key, pay only for what you use.
Overview
Aider is a command-line tool that lets you pair-program with LLMs directly in your terminal. Point it at a git repo, tell it what you want to change in plain English, and it edits your source files and commits the results. It's not a code completion plugin or an IDE — it's a conversation-driven coding partner that works alongside whatever editor you already use.
What sets Aider apart from GUI-based AI coding tools is its deep git integration. Every change Aider makes is automatically committed with a descriptive message, giving you a clean history and easy rollback. It builds a "repo map" using tree-sitter to understand your project's structure — classes, functions, imports — so it can make accurate edits across multiple files without losing context.
Aider supports a wide range of models including Claude Sonnet/Opus, GPT-4o, Gemini, DeepSeek, and local models via Ollama. Since it's BYOK (bring your own key), you pay only for the API calls you make. This makes it especially popular with developers who want maximum flexibility and transparency over costs, and who don't want to abandon their existing terminal-centric workflow for a new IDE.
Key features
Terminal-based
Runs entirely in the terminal with no GUI overhead. Works seamlessly with tmux, SSH sessions, and remote dev environments. Integrates with your existing editor and shell workflow.
Git-native
Every AI-generated change is automatically committed with a descriptive message. Clean diffs, easy rollbacks, and full audit trail of what the AI changed and why.
Multi-model
Supports Claude, GPT-4o, Gemini, DeepSeek, Llama, and dozens more via OpenAI-compatible APIs or Ollama for local models. Switch models mid-session with /model.
Pricing
Free tier: The tool itself is completely free and open-source. You pay only for LLM API usage from your chosen provider.
| Plan | Price | What's included |
|---|---|---|
| Aider (tool) | Free | Open-source, install via pip, unlimited usage |
| LLM API costs | Pay-per-use | You pay your LLM provider directly — typically $0.01–$0.10 per coding request depending on model |
Open-source, install via pip, unlimited usage
You pay your LLM provider directly — typically $0.01–$0.10 per coding request depending on model
Pros & cons
Pros
- ✓Completely open-source with an active community and frequent updates
- ✓Automatic git commits give a clean audit trail and easy rollback for every AI change
- ✓Works with any LLM — swap between Claude, GPT, Gemini, or local models freely
- ✓No IDE lock-in: use it alongside Vim, Emacs, VS Code, or anything else
Cons
- ×Terminal-only interface has a steep learning curve for non-CLI users
- ×Requires your own API keys — no turnkey experience like Cursor or Copilot
- ×No inline code completion or real-time suggestions; it's conversation-driven only
- ×Large codebases can burn through API tokens quickly with repo-map context
How it compares
| Tool | Best for | Pricing | Score |
|---|---|---|---|
| Aider | — | Free (BYOK — pay your LLM provider) | 8.6/10 |
| Cursor | — | Freemium | 9.5/10 |
| GitHub Copilot | — | From $10/mo | 9.3/10 |
| Windsurf | — | Freemium | 9.1/10 |