When was GPT-5.1-Codex released?

GPT-5.1-Codex was released by OpenAI on Thursday, Nov 13 2025.

Who made GPT-5.1-Codex?

GPT-5.1-Codex was built by OpenAI. Creators of ChatGPT and the GPT series of models. Pioneered large-scale language model research.

What benchmark scores did GPT-5.1-Codex get?

GPT-5.1-Codex reports 1 tracked benchmark score — BullshitBench v2: 32%. Tracked scores may come from lab reports or independent benchmarks; source details accompany the benchmark data.

What is the context window of GPT-5.1-Codex?

GPT-5.1-Codex has a context window of 400k. Providers may specify separate input and output token limits.

Is GPT-5.1-Codex open source?

No. GPT-5.1-Codex is a closed model. The weights are not published — it is available only through the provider's own API, apps, or partner platforms.

What came before and after GPT-5.1-Codex?

OpenAI's previous tracked release was GPT-5.1 on Nov 12 2025, 1 day earlier. It was followed by GPT-5.1-Codex-Mini on Nov 13 2025.

GPT-5.1-Codex

Released Nov 13 2025

GPT-5.1-Codex is an AI model released by OpenAI on Thursday, Nov 13 2025, 1 day after GPT-5.1. It has a 400k token context window. Benchmark results (shown below) cover BullshitBench v2.

Benchmarks

BullshitBench v2via BullshitBench

32%

#60 of 100

Compare GPT-5.1-Codex with

GPT-5.1-Codex

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About

OpenAI introduced GPT-5.1-Codex on November 13, 2025 for coding tasks that required multiple rounds of tool use. It shipped alongside a smaller Codex model.

The Codex CLI and IDE extension selected GPT-5.1-Codex by default on macOS and Linux. On Windows, they initially selected the general GPT-5.1 model.

Frequently asked questions

: GPT-5.1-Codex was released by OpenAI on Thursday, Nov 13 2025.
: GPT-5.1-Codex was built by OpenAI. Creators of ChatGPT and the GPT series of models. Pioneered large-scale language model research.
: GPT-5.1-Codex reports 1 tracked benchmark score — BullshitBench v2: 32%. Tracked scores may come from lab reports or independent benchmarks; source details accompany the benchmark data.
: GPT-5.1-Codex has a context window of 400k. Providers may specify separate input and output token limits.
: No. GPT-5.1-Codex is a closed model. The weights are not published — it is available only through the provider's own API, apps, or partner platforms.
: OpenAI's previous tracked release was GPT-5.1 on Nov 12 2025, 1 day earlier. It was followed by GPT-5.1-Codex-Mini on Nov 13 2025.