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

gpt-5.1-codex-max on Vivgrid: an extended-effort Codex coding model on the Responses API with a 400K context window and geo-distributed acceleration.

`gpt-5.1-codex-max` is the extended-effort variant of OpenAI's Codex 5.1 line, tuned to push harder on difficult, long-horizon coding problems. It runs on the **Responses API** and is a good fit when you want maximum reasoning depth from the 5.1 Codex generation.

On Vivgrid it offers a **400K-token context window** and geo-distributed acceleration across **AMER and EMEA**, balancing depth with responsive latency.

## Specifications

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

## 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-max` 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 '{
    "model": "gpt-5.1-codex-max",
    "input": "Refactor this function and explain the change.",
    "stream": true
  }'
```

## Ideal use cases

- Hard, multi-file engineering tasks needing extra reasoning effort
- Codex agents tackling complex debugging and architecture changes
- Long agent loops where thoroughness matters more than raw speed
- Responses-API tooling that wants the strongest 5.1 Codex option

## Related models

- [gpt-5.1-codex](/content/docs/models/gpt-5.1-codex/index.html) — the standard-effort 5.1 Codex model
- [gpt-5.3-codex](/content/docs/models/gpt-5.3-codex/index.html) — newer Codex generation
- [gpt-5.5](/content/docs/models/gpt-5.5) — flagship coding model

[gpt-5.2-codex \ 
\
gpt-5.2-codex on Vivgrid: a Codex-tuned coding model on the Responses API with a 400K context window, function calling, and regional acceleration.](/content/docs/models/gpt-5.2-codex/index.html) [gpt-5.1-codex \ 
\
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.](/content/docs/models/gpt-5.1-codex/index.html)