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- Nov 19, 202595% CONFIDENCEfrom help.openai.com
GPT-5.1-Codex-Max Released
- GPT-5.1-Codex-Max was released on November 19, 2025 as OpenAI's new frontier agentic coding model, available that day in Codex (CLI, IDE extension, cloud, code review) with API access coming soon[1][3]
- Available on Plus, Pro, Business, Edu and Enterprise plans, replacing GPT-5.1-Codex as the Codex default[3]
Notable features
- It is the first model trained natively to work across multiple context windows via compaction, over millions of tokens, with internal tasks running more than 24 hours, and the first trained to operate in Windows environments[3]
- On SWE-bench Verified at medium effort it beats GPT-5.1-Codex using 30% fewer thinking tokens; a new Extra High ('xhigh') effort was added[3]
- Evals (GPT-5.1-Codex high vs Max xhigh): SWE-bench Verified 73.7% vs 77.9%, Terminal-Bench 2.0 52.8% vs 58.1%[3]
- In the API it is available only through the Responses API, taking text and image input, with a 400,000-token context window, up to 128,000 output tokens, a September 30, 2024 knowledge cutoff and pricing of $1.25 per million input and $10 per million output tokens[2]
- Safety: below High cybersecurity capability under the Preparedness Framework but the most capable cyber model deployed to date; Codex sandbox on by default with network off[3]
References 390% CONFIDENCE
The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
- [1]95%OpenAI Model Release Notes: Introducing GPT-5-Codex-Max (November 19, 2025)help.openai.com· Posted Sep 19, 2026· Starts Nov 19, 2025· 33% of score
OpenAI's[2][3] own model release notes date this entry November 19, 2025
- [2]90%GPT-5.1-Codex-Max Model | OpenAI APIdevelopers.openai.com· Added Sep 22, 2026· 34% of score
OpenAI's[1][3] API model page for GPT-5.1-Codex-Max says it is "purpose-built for agentic coding", Responses-API only, with a 400,000 context window, 128,000 max output tokens and $1.25/$10 per 1M tokens.
- [3]85%GPT-5.1-Codex-Maxopenai.com· Added Sep 19, 2026· Starts Nov 19, 2025· 33% of score
OpenAI's[1][2] announcement post, linked from the release note entry.
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