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

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

pip install aider-chat

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

# GPT-4o is the best model, used by default

# GPT-4 Turbo (1106)
aider --4-turbo

# GPT-3.5 Turbo
aider --35-turbo

# List models available from OpenAI
aider --models openai/

You can use aider --model <model-name> to use any other OpenAI model. For example, if you want to use a specific version of GPT-4 Turbo you could do aider --model gpt-4-0125-preview.