Aider

Free

Aider is a terminal-based AI pair programmer that edits your actual files and commits changes to Git. You type plain English at a prompt, and it writes code across multiple files at once.

Aider is a Coding Assistants tool that lives in your terminal. It connects to cloud or local language models and maps your entire codebase so the AI understands how files relate.

Every change becomes a Git commit with a descriptive message. You can review, undo, or revert with standard Git commands.

It works with over 100 programming languages. You bring your own API keys for OpenAI, Anthropic, DeepSeek, or run it air-gapped with local models via Ollama.

Open it if you live in the terminal and want control over every change. Skip it if you want a polished GUI or autonomous AI that runs without your approval.

You get the most from it when your work looks like this.

• Developers comfortable in terminal environments: You already type Git commands and navigate with the keyboard. Aider feels like another shell tool.
• Teams wanting Git discipline with AI-assisted coding: Every AI change lands as a commit you can audit, revert, or cherry-pick later.
• Users wanting model flexibility and cost control: Switch from GPT-4 to DeepSeek mid-session, or use local models to avoid API costs.
• Privacy-conscious developers using local models: Run completely offline with Ollama or LM Studio for air-gapped projects.
• Projects requiring multi-file refactoring: The repo map helps the AI coordinate changes across many files without blowing your token budget.
• Developers prioritizing terminal speed and Git transparency: No IDE lag, no hidden changes. You see diffs before they hit disk.
• Teams needing audit trails and rollback capabilities: The commit history shows exactly what AI touched and when.
• Developers who switch editors frequently: Terminal-based means it works with Vim, VS Code, or any editor—you are not locked in.

These are the parts that stick after a few sessions.

• Automatic Git commits with descriptive messages: You never forget what the AI changed. Your history stays readable.
• The /undo command: Made a mistake? One command rolls back. No manual Git surgery required.
• Model-agnostic switching: Use Claude for planning, DeepSeek for cheap bulk edits, or local models for sensitive code.
• Repository mapping: The AI understands your codebase structure without you pasting files into chat.
• Terminal-native workflow: No context switching. You stay in your shell where you already work.

The path is simple once installed.

1. Start Aider in your repo and add files to context with /add.
2. Describe what you want in plain English at the prompt.
3. Review the diff before it commits, or use /undo if something looks off.
4. Switch models mid-session with /model if you need different capabilities or pricing.

Skip it when these limits would slow you down.

• No GUI for diff previews: You review changes in the terminal or with external tools. There is no slick visual interface.
• Manual context management: You must remember to /add and /drop files. Forget this and the AI lacks context or gets overloaded.
• Setup friction: You manage API keys, Python environments, and model selection yourself. Beginners may struggle.
• Terminal-first limits accessibility: If you avoid the command line, this is not your tool.