GPT-5.1-Codex Max

gpt-5.1-codex-max · OpenAI

GPT-5.1-Codex-Max is a frontier programming model built for the agent-driven era. Powered by an upgraded core reasoning architecture, it is specially trained for complex agentic tasks in software engineering, mathematics, and scientific research. It delivers faster performance, greater stability, and higher token efficiency across the entire development lifecycle, including code generation, refactoring, debugging, and engineering collaboration. With native support for multiple context windows and a built-in compaction mechanism, the model can coherently process millions of tokens within a single task.

API Pricing

Input$1.25 / 1M tokens
Output$10 / 1M tokens
Cache read$0.125 / 1M tokens

Specifications

Context400K tokens
Modalitiestext, image
CapabilitiesThinking, Streaming, Tool calling, Web search, Structured outputs, Prompt caching

Frequently asked questions

What is GPT-5.1-Codex Max?

GPT-5.1-Codex-Max is a frontier programming model built for the agent-driven era. Powered by an upgraded core reasoning architecture, it is specially trained for complex agentic tasks in software engineering, mathematics, and scientific research. It delivers faster performance, greater stability, and higher token efficiency across the entire development lifecycle, including code generation, refactoring, debugging, and engineering collaboration. With native support for multiple context windows and a built-in compaction mechanism, the model can coherently process millions of tokens within a single task.

What is the context length of GPT-5.1-Codex Max?

GPT-5.1-Codex Max has a 400,000 token context window.

How much does GPT-5.1-Codex Max cost?

On AIHubMix, GPT-5.1-Codex Max costs $1.25 per million input tokens and $10 per million output tokens. Cached input reads are billed at $0.125 per million tokens.

What modalities does GPT-5.1-Codex Max support?

GPT-5.1-Codex Max accepts text and image input.

What capabilities does GPT-5.1-Codex Max support?

GPT-5.1-Codex Max supports function calling, structured outputs and thinking. Per-protocol parameter support is listed in the capability table on this page.

How do I call GPT-5.1-Codex Max via API?

GPT-5.1-Codex Max is available through the AIHubMix unified API. The API is OpenAI-compatible: point your OpenAI SDK at https://aihubmix.com/v1, use your AIHubMix API key, and set the model name to gpt-5.1-codex-max — no other code changes needed.

Who created GPT-5.1-Codex Max?

GPT-5.1-Codex Max is developed by OpenAI. AIHubMix aggregates it alongside models from other providers behind one API and one bill.

When was GPT-5.1-Codex Max released?

GPT-5.1-Codex Max was released on November 13, 2025 by OpenAI.

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Use GPT-5.1-Codex Max via the AIHubMix unified API — one interface for every major LLM.