OpenAI: GPT-5.1-Codex-Max

GPT-5.1-Codex-Max is OpenAI’s latest 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.

• Context window: 400,000 tokens
• Input: text, image
• Output: text
• Pricing: $1.25/M input tokens, $10/M output tokens

View on OpenRouter. Model data sourced from OpenRouter.