GPT-5.1 Codex Max is OpenAI's agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic workflows spanning software engineering, mathematics, and research. GPT-5.1 Codex Max delivers faster performance, improved reasoning, and higher token efficiency across the development lifecycle.
Try Now400,000 tokens
128,000 tokens
$1.25
$10
$0.125
$15
$0.19
Superseded by GPT-5.2 Codex; variant discontinued