# gpt-5.1-codex — API, Pricing & Context Window

gpt-5.1-codex on Vivgrid: a Codex-tuned coding model on the Responses API with a 400K context window and three-region geo-distributed acceleration.

`gpt-5.1-codex` is OpenAI's Codex-tuned 5.1 coding model, designed for agentic software engineering through the **Responses API**. It is a well-rounded, cost-effective option for everyday coding agents.

Vivgrid accelerates `gpt-5.1-codex` across **AMER, EMEA, and APAC** — the broadest reach in the Codex line — with a **400K-token context window** for project-scale sessions.

## Specifications

|     |     |
| --- | --- |
| **Provider** | OpenAI |
| **Model ID** | `gpt-5.1-codex` |
| **Best for** | Coding |
| **Context window** | 400,000 tokens |
| **Max output** | 128,000 tokens |
| **Modalities** | Text, Image, Audio |
| **Tool / function calling** | Yes |
| **Knowledge cutoff** | 2024-09 |
| **Acceleration** | ⚡ Geo-Distributed — AMER, EMEA, APAC |

## Pricing

Pricing in USD per 1M tokens, matching the provider's rates.

| Input | Cached input | Output |
| --- | --- | --- |
| $1.25 | $0.125 | $10.00 |

## Quick start

Call `gpt-5.1-codex` through Vivgrid's unified, OpenAI-compatible endpoint. Get an API key from the [Vivgrid Console](https://console.vivgrid.com/).

```
curl https://api.vivgrid.com/v1/responses \
  -H "Authorization: Bearer $VIVGRID_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{\n    "model": "gpt-5.1-codex",\n    "input": "Refactor this function and explain the change.",\n    "stream": true\n  }'  
```

## Ideal use cases

- Day-to-day coding agents on the Responses API
- Globally distributed teams needing low latency in three regions
- Automated edits, reviews, and test generation
- Tool-calling workflows that chain editor and shell actions

## Related models

- [gpt-5.1-codex-max](/content/docs/models/gpt-5.1-codex-max/index.html) — extended-effort variant
- [gpt-5.2-codex](/content/docs/models/gpt-5.2-codex/index.html) — the next Codex generation
- [gpt-5.1](/content/docs/models/gpt-5.1) — general-purpose 5.1 model