OpenAI adds GPT-6.1 Sol to its API

OpenAI's API changelog lists GPT-6.1 Sol (model ID gpt-6.1-sol) as released on September 29, 2026, describing it as a model for complex coding and professional work at a lower cost than GPT-6 Astra. The changelog says it is available through the Responses and Chat Completions endpoints. Separate changelog entries on the same date add computer use to the Agents API and an Ultrafast mode for GPT-6 Astra in the Responses API. GPT-6.1 Sol is a hosted model; OpenAI has not published its weights.1