# GPT-5.1-Codex

GPT-5.1-Codex is an AI model released by OpenAI on Nov 13 2025. It has a 400k context window. Tracked results include 32% on BullshitBench v2.

## Facts

| Field | Value |
| --- | --- |
| Model | GPT-5.1-Codex |
| Developer | OpenAI |
| Release date | Thursday, Nov 13 2025 |
| Licensing | Closed |
| Context window | 400k |

## Tracked benchmark scores

| Benchmark | Score | Source | What it measures |
| --- | --- | --- | --- |
| BullshitBench v2 | 32% | [BullshitBench](https://github.com/petergpt/bullshit-benchmark) | Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. |

## About GPT-5.1-Codex

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.

## Questions and answers

### 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.


---

Canonical page: https://aireleasetracker.com/model/openai/gpt-5.1-codex
Site index: https://aireleasetracker.com/llms.txt
Source: AI Release Tracker (https://aireleasetracker.com). Most benchmark scores come from lab launch material; gathered results identify the leaderboard that published them.