Aider

The terminal is where serious coding happens — and increasingly, it’s where AI coding happens too. Aider is the open-source tool that turned the terminal into an AI pair-programming workspace: it reads your git repository, edits files directly, and commits with sensible messages, using whatever LLM you choose. This guide covers what Aider is, how it works, and how it compares to the other AI coding agents.

For a broader look at AI coding tools, our guide to the best AI tools in 2026 and the Developer Tools directory are great companions.

What is Aider?

Aider is an open-source AI pair programming tool that runs in your terminal. Created by Paul Gauthier, it pioneered the idea that the best interface for AI coding is the one developers already live in: the command line, with git underneath.

Unlike chat-based assistants where you paste code back and forth, Aider:

• Reads your repository and builds a map of its structure
• Edits files directly when you describe a change
• Auto-commits to git with clear, conventional messages
• Works with any LLM — OpenAI, Anthropic, Google, or local models

It’s free, open source, and has become one of the most popular terminal AI tools — with a large community and rapid development.

How Aider works

Aider’s core loop is built around git:

1. You launch Aider in your repository directory.
2. You describe a change in plain language: “add validation to the signup form.”
3. Aider plans — it identifies the relevant files using its repo map.
4. Aider edits — it modifies the code directly in your working tree.
5. Aider verifies — it can run tests or lint commands you configure.
6. Aider commits — it stages the changes and creates a commit with a descriptive message.

Because everything flows through git, every change is reviewable and reversible. You can see exactly what the AI did, in a normal diff, before you push it.

Key features of Aider

Direct file editing with git auto-commit

The signature feature: Aider edits files and commits automatically, so every change is tracked, described, and revertible. You review a normal git diff — no magic, no mystery.

Any LLM you want

Aider is model-agnostic: ChatGPT, Claude, Gemini, DeepSeek, or local models via Ollama. You’re never locked into one provider, and you can switch models for different tasks.

Repo map for large codebases

Aider builds a map of your repository so it understands architecture — which files matter for your request — even in large projects with hundreds of files.

Multi-file and multi-language

Aider handles changes across many files and languages, with strong support for refactoring, testing, and dependency updates.

Chat and script modes

Use it interactively in the terminal, or drive it programmatically in scripts and CI pipelines for automated changes.

Aider vs. Claude Code vs. Codex CLI

	Aider	Claude Code	OpenAI Codex CLI
Open source	✅ Apache-2.0	❌	✅ Apache-2.0
Model choice	✅ Any LLM	Claude only	OpenAI models
Git auto-commit	✅ Core feature	Yes	Yes
Sub-agents	❌	✅ Yes	Limited
Best for	Model-agnostic pairing	Deep agentic autonomy	OpenAI stack

Aider wins on flexibility — any model, fully open, git-native. Claude Code is more agentic with sub-agents and MCP. OpenAI Codex CLI is the choice when you want OpenAI’s models in the terminal. Many developers use more than one.

Who is Aider for?

• Developers who live in the terminal and want AI that edits their repo.
• Teams with git-based workflows — every AI change is a reviewable commit.
• Users of local or open models — Aider connects to Ollama and llama.cpp.
• Open-source enthusiasts who want full control and no lock-in.

It’s not for non-git projects, GUI-first developers, or beginners who’d be more comfortable in an IDE. For those, GitHub Copilot or ChatGPT may be better starting points.

How to get started with Aider

1. Install Aider — pip install aider-chat (Python required).
2. Configure a model — set your API key for OpenAI, Anthropic, or your local model.
3. Open it in a repo — cd your-project && aider.
4. Describe a small change — start with a focused task like adding error handling.
5. Review the diff — Aider shows you exactly what it changed.
6. Scale up — refactors, multi-file changes, and scripted automation.

Start with a small, well-scoped change to build trust, then let Aider tackle larger work as you get comfortable.

The bottom line

Aider is the open, model-agnostic way to do AI pair programming in the terminal. Its git-native design — direct edits, auto-commits, reviewable diffs — fits how real developers work, and its freedom to use any LLM means you’re never locked in. For terminal developers, it’s an essential tool.

For deeper agentic coding with sub-agents, pair it with Claude Code or OpenAI Codex CLI, and explore the full Developer Tools directory.

Official resource: Aider.