OpenAI: GPT-5.1-Codex-Max

GPT-5.1-Codex-Max is a paid, closed-weights model from OpenAI that accepts text and image inputs and supports tool use and reasoning. Its 400,000-token context window accommodates long documents, extended conversations, and multi-file code reviews, while its 128,000-token output ceiling suits tasks that require lengthy generated content. Structured output support is not confirmed from available data. At $1.25 per million input tokens and $10.00 per million output tokens, the output cost is on the higher end of the current market, which makes per-query expense a real consideration for high-volume applications. More importantly, there is no independent benchmark coverage yet, so its actual performance relative to competing models is unverified. Buyers who need a large context window, tool calling, and image understanding from an OpenAI-hosted product may find it worth evaluating, but those who require third-party performance validation before committing should wait for benchmark data to emerge.