GPT-5.1-Codex-Max coding

openrouter
openai
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.

Capabilities

Context Window 400k tokens
Max Output 128k tokens
Inputs
Outputs

Pricing (per 1M tokens)

Input $1.25
Output $10.00
Cache Read $0.12
Cache Write -

Supported Parameters

include_reasoningmax_tokensreasoningresponse_formatseedstructured_outputstool_choicetools

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