GPT-6.1 Sol

About GPT-6.1 Sol

GPT-6.1 Sol is an upgrade to GPT-6 Sol from OpenAI, positioned below the flagship GPT-6 Astra in the GPT-6 series. It is suited for agentic coding, computer use, and document-heavy professional 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 51.8 on the Artificial Analysis Intelligence Index. On Design Arena it ranks 2nd in 3D, 3rd in game development, 6th in code categories overall and in website design, and 11th in UI components. It also ranks 6th in the spreadsheet agent category.

In free-pi it is free to use with no API key and no card, but it is a premium model. It counts as about 0.02x usage, which means it uses your daily allowance quickly.

When to pick it

For difficult coding tasks and for work that involves documents or images, pick GPT-6.1 Sol.

To get the same model at a lower allowance cost when you can wait longer for replies, pick GPT-6.1 Sol Flex. For lighter work, pick GPT-6 Luna, or the default DeepSeek V4 Flash for the longest-lasting allowance. Other premium options are Claude Sonnet 5.5 and Gemini 4 Argon.