# GPT-5.1-Codex

[Canonical model page](https://headlessthrones.com/models/gpt-5-1-codex) · [Model library](https://headlessthrones.com/models)

Public catalog reference from Headless Thrones. Exact catalog ID: `gpt-5-1-codex`. Catalog source-check date: 2026-10-23.

This brief contains the public catalog answers and any catalog guide, not private drafts, historical editorial revisions or independently measured rankings. The canonical HTML page may also display separately published editorial.

Current catalog answers

## What to know about GPT-5.1-Codex

AI-compiled from linked model documentation. This is a catalog reference, not an independent performance review. Catalog checked October 23, 2026.

[Token limits](https://headlessthrones.com/models/gpt-5-1-codex#model-answer-context) · [Exact model](https://headlessthrones.com/models/gpt-5-1-codex#model-answer-identity) · [Access](https://headlessthrones.com/models/gpt-5-1-codex#model-answer-access) · [Dates & knowledge](https://headlessthrones.com/models/gpt-5-1-codex#model-answer-dates) · [Inputs & outputs](https://headlessthrones.com/models/gpt-5-1-codex#model-answer-modalities)

### What are GPT-5.1-Codex's context and output limits?

The documented **context window is 400,000 tokens**. [Source](https://developers.openai.com/api/docs/models/gpt-5.1-codex)

The documented **maximum output is 128,000 tokens**. [Source](https://developers.openai.com/api/docs/models/gpt-5.1-codex)

Context, input and output limits describe different constraints. Do not add the figures together to infer a larger window. Check the endpoint's accounting for conversation history, system instructions, tools, media and generated tokens; a documented maximum is not a guarantee of answer quality or a measured usable capacity.

### Which GPT-5.1-Codex does this page describe?

GPT-5.1-Codex is a model record from **OpenAI** in the Codex family. [Source](https://developers.openai.com/api/docs/models/gpt-5.1-codex)

The recorded model identifier or checkpoint is `gpt-5.1-codex`. Use that exact identifier when checking documentation or a provider listing. [Source](https://developers.openai.com/api/docs/models/gpt-5.1-codex)

### How can you access GPT-5.1-Codex?

The catalog records the historical **API** access route for GPT-5.1-Codex. [Source](https://developers.openai.com/api/docs/models/gpt-5.1-codex)

As of the catalog check, this version was marked retired. [Source](https://developers.openai.com/api/docs/deprecations) Check the linked lifecycle information before starting a new integration.

For a new integration, use the publisher’s replacement guidance and check its current account, region and endpoint requirements. Historical API access does not mean the retired endpoint can still be called.

### What dates are documented for GPT-5.1-Codex?

**Knowledge cutoff: September 30, 2024.** [Source](https://developers.openai.com/api/docs/models/gpt-5.1-codex) This labels the documented knowledge boundary; it is not a promise that every earlier fact is known or correct.

Retrieval or web tools can supply newer information at run time. That does not change the model's recorded training or knowledge dates, and this record does not establish that a particular endpoint includes those tools.

### What can GPT-5.1-Codex receive and generate?

Documented inputs: **text and image**. [Source](https://developers.openai.com/api/docs/models/gpt-5.1-codex)

Documented outputs: **text**. [Source](https://developers.openai.com/api/docs/models/gpt-5.1-codex)

Input support and output generation are separate capabilities. Reading an image does not establish image generation; a text output listing does not establish speech output. File sizes, formats and media limits depend on the documented implementation.

**Catalog qualifications:** Vendor API shutdown date: 2026-07-23.

**Evidence still missing here:** complete input/output pricing. Missing documentation is not evidence that a feature is unavailable.

Headless Thrones has not independently benchmarked this model for this reference. Evaluate it on representative work before choosing it; these facts do not rank its accuracy, reliability, speed or suitability against another model.

Keep the exact version in view

## Other Codex models from OpenAI.

These are separate records in the same publisher family. A shared family name does not establish equal capabilities or interchangeable licenses.

### [codex-mini-latest](https://headlessthrones.com/models/codex-mini-latest)

API · 200,000 context tokens

### [GPT-5-Codex](https://headlessthrones.com/models/gpt-5-codex)

API · 400,000 context tokens

### [GPT-5.1-Codex Mini](https://headlessthrones.com/models/gpt-5-1-codex-mini)

API · 400,000 context tokens

### [GPT-5.1-Codex-Max](https://headlessthrones.com/models/gpt-5-1-codex-max)

API · 400,000 context tokens

### [GPT-5.2-Codex](https://headlessthrones.com/models/gpt-5-2-codex)

API · 400,000 context tokens

### [GPT-5.3-Codex](https://headlessthrones.com/models/gpt-5-3-codex)

API · 400,000 context tokens