Aider Installation Guide

Aider is AI pair programming in your terminal. It edits files, runs your tests and commits each change to git, so you always have a clean undo.

System Requirements

• Python 3.8 to 3.13 (Aider installs Python 3.12 for itself if you need it)
• git — Aider works in a repository and commits as it goes
• An API key for one of the supported providers, or a local model through Ollama or LM Studio

Installation Instructions

The One-Line Installer (Recommended)

# macOS and Linux
curl -LsSf https://aider.chat/install.sh | sh
 
# Windows PowerShell
powershell -ExecutionPolicy ByPass -c "irm https://aider.chat/install.ps1 | iex"

The script installs Aider in its own separate Python environment, and installs Python 3.12 for it if the system does not have a suitable version.

With uv

python -m pip install uv
uv tool install --force --python python3.12 --with pip aider-chat@latest

With pipx

python -m pip install pipx
pipx install aider-chat

With pip

Use a virtual environment, otherwise you will fight with dependencies:

python -m venv ~/.venvs/aider
source ~/.venvs/aider/bin/activate
python -m pip install -U --upgrade-strategy only-if-needed aider-chat

Connecting a Model

# Anthropic
export ANTHROPIC_API_KEY=sk-ant-...
aider --model sonnet
 
# OpenAI
export OPENAI_API_KEY=sk-...
aider --model gpt-4o
 
# Google Gemini
export GEMINI_API_KEY=...
aider --model gemini/gemini-2.5-pro
 
# DeepSeek
export DEEPSEEK_API_KEY=...
aider --model deepseek
 
# A local model through Ollama
aider --model ollama/qwen2.5-coder:32b
 
# GitHub Copilot
aider --model copilot/sonnet

# List everything Aider can talk to
aider --models

Put the keys in a .env file next to your project — Aider reads it automatically — and add it to .gitignore:

echo ".env" >> .gitignore

Your First Session

cd /to/your/project
aider --model sonnet --api-key anthropic=$ANTHROPIC_API_KEY

# In the chat
Add a --verbose flag to the CLI that prints the current config on startup.

Aider will:

1. Read the relevant files
2. Show you the diff it proposes
3. Apply the change and commit it

Useful Flags

# Add files explicitly to the context
aider src/parser.py
 
# Let Aider find the relevant files itself
aider --read docs/architecture.md
 
# Skip the git repo (Aider warns when you are not in one)
aider --no-git
 
# Use a specific file to describe the style you want
aider --edit-format diff
 
# Run your test command after every change
aider --test-cmd "pytest -q"

In-Chat Commands

Architect Mode

For bigger changes, let a stronger model plan and a cheaper model implement:

/architect Design a caching layer for the API and write out the plan.
/code Now implement that plan.

Troubleshooting

Best Practices

1. Always work in a git repository — Aider commits every change, so you always have an undo.
2. Commit your work before you start so the history is readable.
3. Set the test command with --test-cmd so Aider can verify its own changes.
4. Keep a .env file for keys and add it to .gitignore.
5. Use architect mode for anything that touches more than two files.
6. Review the diff before you accept a change.
7. Be specific — describe the behaviour you want, not just the function names.
8. Use /undo freely; it is cheap.

Next Steps

• Aider Documentation
• Aider on GitHub
• Claude Code
• Goose
• Git Installation Guide