Aider

Aider is an open-source tool for AI pair programming in your terminal. You run it inside a git repository, tell it what you want, and it edits your local files to make the change. Its defining habit is that it commits each change to git with a written commit message, so every step the model takes is tracked and reversible. It is released under the Apache-2.0 license and is written in Python.

Aider works with your existing editor rather than replacing it. You keep editing files however you normally do, and Aider watches the repository, applies its own edits as commits, and can pick up comments you leave in the code as instructions. This makes it a common choice for engineers who want an agentic loop over their code without leaving the command line or adopting a new IDE.

Where Aider sits in the stack

Installation

The recommended installer sets up Aider in its own isolated environment so it does not clash with your project’s Python packages.

python -m pip install aider-install
aider-install

There are also one-line installers for each platform.

# macOS and Linux
curl -LsSf https://aider.chat/install.sh | sh

Two ways to use it

The first pattern is to launch Aider against a model with an API key. You start it in your project directory, and it opens a chat where you describe changes.

cd /to/your/project
aider --model sonnet --api-key anthropic=<key>
# or another provider
aider --model deepseek --api-key deepseek=<key>

The second pattern is Aider’s two-step architect mode. One model acts as the architect and proposes a solution in plain language; a second editor model turns that proposal into concrete file edits. This often produces better results on harder changes than asking a single model to plan and edit at once.

# inside an aider session
/ask how should we add rate limiting to the API layer?   # discuss, no edits
/architect add token-bucket rate limiting to the API      # plan, then edit
/undo                                                      # revert the last change if needed

By default Aider is in code mode and edits directly. /ask discusses without touching files, and /architect runs the plan-then-edit workflow. Every edit becomes its own git commit.

Typical workflow

How it compares

When not to use it

• You do not use git. Aider’s commit-per-change workflow is the core of the tool. Without a git repository you lose the tracking and /undo that make it valuable.
• You want a graphical editor. Aider is terminal-first. If you want an AI panel inside a full IDE, Cursor or Cline fits better.
• You want a bundled free model. Aider is bring-your-own-model. You supply an API key for a cloud model or run a local one; there is no included allowance.
• You need multi-surface access. Aider runs in one terminal on one machine. For a persistent agent reachable from chat apps, see Hermes Agent .

Further reading

• Aider documentation : official install, model setup, and usage guides.
• Aider on GitHub : source and issues under the Apache-2.0 license.
• Aider modes reference : the code, architect, and ask modes explained.
• Open-source coding agents compared : where Aider sits among the alternatives.
• OpenCode : a provider-agnostic terminal agent with a build and plan agent system.
• Agentic loops : the read-plan-edit-run cycle every coding agent runs.

Sources

• Aider website : definition, feature list, git auto-commit, repository map, and supported models.
• Aider install guide : official install commands and Python version support.
• Aider on GitHub : Apache-2.0 license, Python, and release history.