OpenAI Coding Big Closed weights

GPT-5.1-Codex-Max

358 days since OpenAI announced it · 19 Nov 2025

GPT-5.1-Codex-Max is a closed-weights coding model from OpenAI, announced 19 Nov 2025. It costs $1.25 per 1M input tokens and $10 per 1M output tokens. Its context window is 400K tokens.

Input: $1.25; per 1M tokens
Cache write: —; per 1M tokens
Cache read: —; per 1M tokens
Output: $10; per 1M tokens
Context window: 400K; tokens
Parameters: —; not disclosed

Announcement: openai.com/index/gpt-5-1-codex-max
Docs: developers.openai.com/api/docs/models/gpt-5.1-codex-max

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OpenAI · Big · Codex

closed weights

GPT-5.3-Codex +49d 5 Feb 2026
GPT-5.2-Codex +29d 18 Dec 2025
GPT-5.1-Codex-Max 19 Nov 2025