Aider
AI pair programming in your terminal with automatic git commits
Aider is an open-source command-line tool that turns any LLM into a pair programmer. You describe what you want in plain English, Aider edits the files directly in your local git repository, and it automatically creates clean, well-described git commits for every change. It supports GPT-4o, Claude, Gemini, DeepSeek, and dozens of other models — you bring your own API key and pick the model that works best for your task.
Visit AiderWhat is Aider?
Aider is a free, open-source AI pair programming tool created by Paul Gauthier that runs entirely in your terminal. Unlike IDE-based tools like Copilot or Cursor that provide inline suggestions as you type, Aider takes a conversational approach: you tell it what you want to change in natural language, and it edits the actual files in your git repository, then commits those changes automatically with descriptive commit messages. It is one of the most popular open-source AI coding tools, with over 25,000 GitHub stars.
What makes Aider stand out in the increasingly crowded AI coding space is its model-agnostic design. While Copilot ties you to OpenAI models and Cursor has its own model routing, Aider works with virtually any LLM available via API: OpenAI's GPT-4o and o1 series, Anthropic's Claude family (Opus, Sonnet, Haiku), Google's Gemini models, DeepSeek, Mistral, and even local models through Ollama or LM Studio. Aider maintains a public coding benchmark leaderboard that tests each model on real coding tasks, so you can make data-driven decisions about which model to use.
Aider's architecture is git-native. When you start Aider in a repository, it understands the repo structure, tracks which files are relevant to the current conversation, and generates proper diffs that it applies directly. Every edit gets its own git commit, which means you can review, revert, or cherry-pick any AI-generated change using standard git workflows. This is a huge advantage for professional developers who need to maintain clean commit histories and want to treat AI contributions the same way they treat human contributions.
The tool is particularly strong for multi-file refactoring, feature implementation across multiple modules, and codebase-wide changes that would be tedious to do manually. Because it runs in the terminal, it works alongside any editor or IDE — your editor picks up file changes in real time. The cost model is transparent: Aider itself is free, and you pay only the API costs of whatever model you choose, typically ranging from $0.50 to $5 per coding session depending on the model and complexity.
Key Features
Multi-Model Support
Works with GPT-4o, Claude, Gemini, DeepSeek, Mistral, Ollama, and dozens more. Switch models mid-session or use different models for different tasks.
Automatic Git Commits
Every edit creates a clean git commit with a descriptive message. Review, revert, or cherry-pick AI changes using standard git workflows.
Multi-File Editing
Edits multiple files in a single conversation. Add files to context, describe what you want, and Aider makes coordinated changes across your codebase.
Repo Map
Automatically builds a map of your repository structure so the model understands the codebase topology. Smart context management keeps relevant code in view.
Public Coding Benchmark
Maintains a regularly updated leaderboard testing each LLM on real coding tasks. Data-driven model selection instead of guesswork.
Open Source (Apache 2.0)
Fully open-source with an active community. Inspect the code, contribute features, or fork it for custom workflows. No vendor lock-in.
Pricing
Aider itself is free and open-source. Your only cost is the API fees from whichever LLM provider you choose to use. Here are typical costs per coding session based on popular model choices.
| Model | Typical Session Cost | Best For | Details |
|---|---|---|---|
| Claude Sonnet | $0.50 – $2 | Everyday coding | Great balance of quality and cost for most tasks |
| GPT-4o | $0.50 – $3 | Complex refactoring | Strong multi-file editing and architecture work |
| Claude Opus | $2 – $10 | Hardest problems | Most capable model for difficult coding challenges |
| DeepSeek / Local | $0 – $0.50 | Budget-friendly | Cheapest option, or free with local models via Ollama |
Costs depend on session length and model choice. See aider.chat for the latest model benchmark results.
Pros & Cons
Pros
- Completely free and open-source — no subscription, no vendor lock-in
- Model-agnostic: use any LLM provider, switch models freely
- Git-native with automatic commits, clean diffs, and easy rollbacks
- Excellent multi-file editing for large refactoring tasks
- Public benchmark leaderboard for data-driven model selection
Cons
- Terminal-only interface has a learning curve for GUI-oriented developers
- No inline code completion — it is a conversation tool, not an autocomplete
- Requires managing your own API keys and understanding token costs
- No built-in team collaboration or enterprise governance features
Alternatives to Aider
If you prefer a GUI over the terminal, or need inline completion alongside conversational editing, these alternatives take different approaches to AI-assisted coding.
Claude
Anthropic's Claude Code offers a similar terminal-based AI coding experience with deep integration into the Anthropic ecosystem.
Cursor
AI-native editor with chat, inline edits, and agent features. Better for developers who want a full GUI experience.
GitHub Copilot
Market-leading inline code completion with Copilot Chat. Best for real-time autocomplete rather than conversational editing.
Windsurf
AI-native editor with Cascade agent for multi-step coding tasks. GUI alternative with strong agentic capabilities.
Frequently Asked Questions
What is Aider?
Aider is a free, open-source AI pair programming tool that runs in your terminal. Created by Paul Gauthier, it lets you describe code changes in plain English and then edits the files directly in your local git repository, automatically creating well-described git commits for each change. It supports dozens of LLMs including GPT-4o, Claude, Gemini, and DeepSeek, and has become one of the most popular open-source AI coding tools with over 25,000 GitHub stars.
Is Aider free?
Yes, Aider itself is completely free and open-source under the Apache 2.0 license. You can install it with a single pip command and start using it immediately. The only cost is the API fees from whichever LLM provider you choose — typically between $0.50 and $5 per coding session depending on the model. You can also use Aider with free local models through Ollama or LM Studio for zero API cost.
How is Aider different from GitHub Copilot?
Copilot is primarily an inline autocomplete tool that suggests code as you type inside your IDE. Aider is a terminal-based conversational tool that makes multi-file edits based on natural language instructions and automatically commits changes to git. Copilot is better for rapid line-by-line coding assistance, while Aider excels at larger tasks like refactoring across multiple files, implementing new features, and making coordinated codebase-wide changes. They can complement each other — many developers use Copilot for autocomplete and Aider for bigger edits.
What models does Aider support?
Aider supports virtually any LLM available via API. Popular choices include OpenAI GPT-4o and o1, Anthropic Claude (Opus, Sonnet, Haiku), Google Gemini (Pro, Flash), DeepSeek, Mistral, and local models through Ollama or LM Studio. Aider maintains a public coding benchmark leaderboard at aider.chat that tests each model on real coding tasks, helping you choose the best model for your needs and budget.
Does Aider work with my IDE?
Aider runs in your terminal alongside any IDE or text editor. When Aider edits files, your IDE detects the changes through its normal file-watching mechanisms and updates in real time. There are also community-built integrations for VS Code, Neovim, and Emacs that provide tighter integration. The core tool is deliberately editor-agnostic — it works with whatever development environment you already use.
What are the best alternatives to Aider?
Top alternatives include Claude Code for another terminal-based AI coding assistant with deep Anthropic integration, Cursor for a full AI-native editor experience with chat and inline edits, GitHub Copilot for inline code completion and autocomplete, and Windsurf for an AI editor with agentic capabilities. Aider's unique advantages are its open-source nature, support for virtually any LLM, automatic git integration, and the public benchmark leaderboard for model comparison.
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