An open-source pair-programming CLI for writing code while talking with an AI in your terminal. Released in June 2023, it has gathered more than 48,000 stars on GitHub. What sets it apart is a design that commits every AI edit straight into Git, plus a “repository map” that summarizes the structure of your whole codebase and hands it to the LLM. It supports over 100 programming languages and connects to major models such as Claude, GPT, Gemini, and DeepSeek, as well as models you run locally. Written in Python, it is ready to use as soon as you install it with pip.
Key Features
- Repository map for whole-codebase awareness: Aider automatically builds a map summarizing the functions, classes, and signatures in your project and passes it to the LLM. Because edits are informed by the whole project rather than just the open file, results hold up even in large repositories
- Changes are auto-committed to Git: Every edit the AI makes is committed automatically with a message reflecting its content. If you dislike the result you can roll it back with ordinary Git operations, so you can safely widen the scope of what you delegate
- Simultaneous multi-file editing: Aider can change several files at once across everything you have added to the conversation. Work that ripples through many files ─ renaming a function, changing an interface ─ can be handled with a single instruction
- Watch mode for editor integration: Aider watches your files for changes and picks up comments you write in the code as instructions. You can keep working in your usual editor, such as VS Code, while Aider implements in the background
- Voice, image, and web page input: You can dictate instructions by voice, hand over screenshots or design images, and pass URLs so the AI can read the referenced documentation
- Automatic lint and test runs: After editing, Aider can run your linter and test commands, then try to fix errors it finds. Anything a machine can catch is caught before a human reviews the generated code
- Model-agnostic, with a public benchmark: It connects to a wide range of commercial and local models, and the official site publishes a leaderboard measuring code-editing performance per model
Pricing
| Plan | Price | What you get |
|---|---|---|
| Aider itself | $0 (open source under Apache-2.0) | All features with no limits. No subscription and no usage caps |
| LLM usage | Pay-as-you-go from each model provider | API charges from Anthropic, OpenAI, Google, DeepSeek, and others apply separately |
| Using local models | $0 (your own compute) | Connect to a local LLM such as Ollama and run without any API charges |
Pricing is as of August 2026. Please check the official site for the latest information.
Aider itself is free open-source software; the only cost is the LLM API you connect it to. Actual spending varies a lot with the model you pick, so it is worth starting with an inexpensive model and switching to a higher-performance one only when you need it.
Pros & Cons
✅ Pros
- Aider itself is entirely free and open source, with no vendor lock-in
- You choose the LLM freely ─ commercial APIs and local models feel the same to use
- Deep Git integration makes AI changes easy to track and revert
- The repository map enables context-aware edits even in large codebases
- Being a CLI, it runs where a GUI is unavailable, such as servers over SSH or CI environments
⚠️ Cons
- LLM API charges are separate, and costs can grow beyond expectations depending on how you use it
- You must obtain and configure API keys in advance, which is a hurdle if you are not comfortable with the CLI or Git
- It is designed around use inside a Git repository, so projects without version control get less benefit
- GUI and IDE integration is limited, making it a poor fit for people who want visual controls
- Output quality depends heavily on the model you connect; weaker models can be overwhelmed by the volume of repository-map context
Comparison with Similar Services
| Criteria | Aider | Claude Code | Codex CLI | Cline |
|---|---|---|---|---|
| Provider | Aider AI | Anthropic | OpenAI | Cline (open source) |
| Environment | Terminal (CLI) | Terminal (CLI) | Terminal (CLI) | VS Code extension |
| License | Apache-2.0 (OSS) | Proprietary | OSS | OSS |
| Models | Any (commercial API or local) | Claude family | Mainly OpenAI models | Any (multiple providers) |
| Cost | Free tool + pay-as-you-go API | Subscription or API billing | Subscription or API billing | Free tool + pay-as-you-go API |
| Git integration | Auto-commits changes | Supported (commits on request) | Supported | Supported |
Who Is It For
- Developers who work mainly in the terminal and want to delegate implementation without leaving it
- People who do not want to be tied to one AI vendor and prefer to swap models freely
- Anyone who wants AI changes recorded as Git history so they can be reviewed and rolled back
- Teams who want AI assistance from local LLMs without sending code outside their environment
- Individual developers who prefer pay-as-you-go costs over a monthly subscription
Summary
Aider is an open-source pair-programming CLI that expresses AI code editing in a unit developers already know: the Git commit. Because the tool is free and the model is yours to choose, it suits people who want to control both cost and which AI they use. On the other hand, it assumes API key setup and CLI familiarity, so it is not aimed at complete beginners. A good starting point is a small repository, an inexpensive model, and a task that touches only a few files.