To work with Anthropic’s models, you need to provide your Anthropic API key either in the ANTHROPIC_API_KEY environment variable or via the --anthropic-api-key command line switch.

Aider has some built in shortcuts for the most popular Anthropic models and has been tested and benchmarked to work well with them:

pip install aider-chat

export ANTHROPIC_API_KEY=<key> # Mac/Linux
setx   ANTHROPIC_API_KEY <key> # Windows

# Claude 3 Opus
aider --opus

# Claude 3.5 Sonnet
aider --sonnet

# List models available from Anthropic
aider --models anthropic/

You can use aider --model <model-name> to use any other Anthropic model. For example, if you want to use a specific version of Opus you could do aider --model claude-3-opus-20240229.