# GPT 5.1 Codex Max API

OpenAI's GPT 5.1 Codex Max, through an OpenAI-compatible API. Providers quote it on an open exchange, and each request goes to the offer with the lowest estimated charge that meets your rules.

- Providers compete for each request. The exchange ranks the offers that meet your rules by estimated charge. It fixes your maximum charge before the first token, and you pay for the tokens that the model uses.
- The OpenAI and Anthropic APIs. Use the OpenAI or Anthropic SDK that you have. Set the base URL and your key, and send gpt-5.1-codex-max as the model.
- Your data rules. Send x-liquid-retention: none and only offers whose provider does not keep your content compete for the request.

## Facts

- Model name: gpt-5.1-codex-max
- Maker: OpenAI
- Context window: 272K tokens
- Input price: $1.247 per million tokens
- Output price: $9.978 per million tokens
- Providers: 1 independent provider
- Regions: us

## Providers

- [Architect](https://liquidinference.ai/providers/805445a7-0e40-4c1b-9baf-7b3b01e30e42.md): us, $1.247 input and $9.978 output per million tokens, $0.125 cache read per million tokens, 272K tokens of context

## Request

```sh
curl https://router.inference.ai.exchange/v1/chat/completions \
  -H "Authorization: Bearer $LIQUID_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.1-codex-max",
    "messages": [{"role":"user","content":"Say hello."}]
  }'
```

## Questions

### What is GPT 5.1 Codex Max?

Served by intent-router: each job goes to the cheapest healthy upstream for this model.

### How much does GPT 5.1 Codex Max cost?

Offers now ask $1.247 per million input tokens and $9.978 per million output tokens. A job pays for the tokens it uses. The exchange picks the cheapest eligible offer.

### What is the context length of GPT 5.1 Codex Max?

The largest offer takes 272,000 input tokens. A smaller offer can take less. The exchange skips an offer that cannot take your message.

### What can GPT 5.1 Codex Max do?

Its providers list Documents, Vision, Reasoning effort, JSON object, JSON schema, Frequency penalty, Logit bias, Log probabilities, Min-p sampling, Presence penalty, Repetition penalty, Seed, Stop sequences, Top-k sampling, Top-p sampling, Text, Tools.

### What inputs and outputs does GPT 5.1 Codex Max support?

Text · Files · Images → Text.

### Which providers serve GPT 5.1 Codex Max?

1 independent provider quote it now, with 1 offer. The table above ranks them by the cost of a typical job.

### How do I call GPT 5.1 Codex Max?

Send "gpt-5.1-codex-max" as the model in an OpenAI or Anthropic request. The API section links to setup steps for each client.

### When was GPT 5.1 Codex Max listed?

The exchange first listed it on 10/8/2026. This is not its release date.

## Related pages

- [This page in a browser](https://liquidinference.ai/models/gpt-5.1-codex-max)
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- [Set up a client](https://liquidinference.ai/connect/gpt-5.1-codex-max)
- [All models](https://liquidinference.ai/models)
- [Providers](https://liquidinference.ai/providers.md)
- [Discover the best model for your budget](https://liquidinference.ai/discover)
- [Quickstart](https://liquidinference.ai/docs/quickstart.md)
- [llms.txt: the index of every page, as Markdown](https://liquidinference.ai/llms.txt)
- [llms-full.txt: every page in one file](https://liquidinference.ai/llms-full.txt)