GPT-6 Luna
Use it free in free-pi
~0.5x usage
npx free-pi-cli
/model gpt-6-lunaAbout GPT-6 Luna
GPT-6 Luna is the fast, cost-efficient model in OpenAI's GPT-6 series, positioned below GPT-6 Sol. It is suited for high-volume and latency-sensitive workloads such as chat, classification, and lightweight agentic work. It became available in September 2026.
The model accepts text, image, and file input and produces text. The context window is 1,050,000 tokens and a response can be up to 128,000 tokens. It supports reasoning with an effort setting, tool calling, and structured outputs. With tool calling, the free-pi agent can read and edit files, run commands, and use free-pi's built-in web search and documentation lookup tools.
It scores 38.1 on the Artificial Analysis Intelligence Index, above the default DeepSeek V4 Flash 0731 (34.3).
In free-pi it is free to use with no API key and no card. It counts as about 0.5x usage, so it uses your allowance faster than the default but much more slowly than the premium models.
When to pick it
For routine coding with an OpenAI model that reads images and files, and without the fast allowance drain of GPT-6.1 Sol, pick GPT-6 Luna. It also has a very large context window, 1,050,000 tokens.
For the same model on a slower tier that lasts longer, pick GPT-6 Luna Flex. For the longest-lasting allowance, pick the default DeepSeek V4 Flash. For harder tasks, pick GPT-6.1 Sol or another premium model.