Aider

AI pair programming in your terminal for new and existing codebases

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Pricing

Free

Open source

Yes

What is Aider?

Aider is an AI pair-programming tool that runs in your terminal. You can use it to start a new project or to edit an existing codebase. It works with cloud models such as Claude 3.7 Sonnet, DeepSeek R1 and V3, OpenAI o1, o3-mini and GPT-4o, and with almost any other LLM, including local models.

Aider builds a map of your whole codebase, which helps it work in larger projects. It supports more than 100 programming languages. Each change is committed to git with a descriptive message, so you can diff or undo edits with the git tools you already use. It can also run your linters and tests after each edit and fix the problems they report.

You install Aider with pip and connect your own model API key. It suits developers who prefer the command line and want AI edits tracked in git.

Key features

Terminal-based AI pair programming
Works with cloud and local LLMs
Map of the whole codebase for larger projects
Supports 100+ programming languages
Auto-commits changes to git with descriptive messages
Runs linters and tests, then fixes problems they find
Uses images and web pages as context
Voice requests and in-IDE code comments

Use cases

Who it's for

Software developersCommand-line usersOpen-source maintainersDevelopers running local LLMs

Editing an existing codebase

Ask for features or fixes across a large repo. Aider uses its codebase map to find the files involved.

Starting a new project

Describe what you want built and let Aider write the first version from the terminal.

Fixing failing tests and lint errors

Aider runs your test suite and linters after it makes changes, then attempts to fix what fails.

Using local or alternative models

Connect DeepSeek, OpenAI, Anthropic or local models instead of being tied to one vendor.

Aider pricing

From the vendor's site, checked Oct 26, 2026; we re-check prices monthly. Prices change — confirm on their pricing page.

The vendor does not publish plan details.

How Aider compares

Aider has a free plan, like all 4 alternatives below.
It is open source, the only one here.

Tool	Starts at	Free trial	API	Open source
AAider	Free	—	—
GGitHub Copilot	$10/mo	—	—	—	Aider vs GitHub Copilot
CCursor	$8/mo	—	—	—	Aider vs Cursor
OOpenAI Codex	$8/mo	—		—	Aider vs OpenAI Codex
WWindsurf	$20/mo	—		—	Aider vs Windsurf

Compare 8 capabilities

Capability	Aider	GitHub Copilot	Cursor	OpenAI Codex	Windsurf
Agent mode	—
Tab completion	—		—	—
CLI / terminal					—
Cloud agents	—
AI PR review	—
Bring your own key		—	—	—	—
Local / self-hosted models		—	—	—	—
MCP support	—			—	—

Capabilities as stated on each vendor's own site; — means the site doesn't say. The closest alternatives in our directory by category. “Starts at” is the cheapest paid plan per month, as each vendor lists it.

Pros and cons

Strengths

Code is public on GitHub
Works with many LLMs, including local models
Every edit is committed to git, so changes are easy to review or undo
Runs linters and tests automatically

Limitations

Terminal-only interface with no GUI app listed
You supply your own model API key
Installed through Python and pip

Aider FAQ

How much does Aider cost?

Aider's website doesn't publish a price or plans. The code is public on GitHub. You use your own LLM API key, so you pay the model provider for usage.

Which models does Aider support?

The site says it works best with Claude 3.7 Sonnet, DeepSeek R1 and Chat V3, OpenAI o1, o3-mini and GPT-4o. It can connect to almost any LLM, including local models.

How do I install Aider?

Run python -m pip install aider-install, then aider-install. After that, start aider in your project directory with your model and API key.

Does Aider work with git?

Yes. It auto-commits each change with a descriptive message, so you can diff or undo edits with standard git tools.