# Grok 4 Fast API

xAI's Grok 4 Fast, 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 grok-4-fast 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: grok-4-fast
- Maker: xAI
- Context window: 2M tokens
- Input price: $0.200 per million tokens
- Output price: $0.501 per million tokens
- Providers: 1 independent provider
- Regions: us

## Providers

- [Architect](https://liquidinference.ai/providers/805445a7-0e40-4c1b-9baf-7b3b01e30e42.md): us, $0.200 input and $0.501 output per million tokens, $0.050 cache read per million tokens, 2M 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": "grok-4-fast",
    "messages": [{"role":"user","content":"Say hello."}]
  }'
```

## Questions

### What is Grok 4 Fast?

Grok 4 Fast is a model from xAI.

### How much does Grok 4 Fast cost?

Offers now ask $0.200 per million input tokens and $0.501 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 Grok 4 Fast?

The largest offer takes 2,000,000 input tokens. A smaller offer can take less. The exchange skips an offer that cannot take your message.

### What can Grok 4 Fast 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 Grok 4 Fast support?

Text · Files · Images → Text.

### Which providers serve Grok 4 Fast?

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 Grok 4 Fast?

Send "grok-4-fast" as the model in an OpenAI or Anthropic request. The API section links to setup steps for each client.

### When was Grok 4 Fast listed?

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

## Related pages

- [This page in a browser](https://liquidinference.ai/models/grok-4-fast)
- [Grok 3 Mini Latest](https://liquidinference.ai/models/grok-3-mini-latest.md)
- [Grok 4 Fast Non Reasoning](https://liquidinference.ai/models/grok-4-fast-non-reasoning.md)
- [Grok 4.1 Fast](https://liquidinference.ai/models/grok-4.1-fast.md)
- [Grok 4 Fast Reasoning](https://liquidinference.ai/models/grok-4-fast-reasoning.md)
- [Grok 4.1 Fast Non Reasoning Latest](https://liquidinference.ai/models/grok-4.1-fast-non-reasoning-latest.md)
- [Grok 4.1 Fast Non Reasoning](https://liquidinference.ai/models/grok-4.1-fast-non-reasoning.md)
- [Set up a client](https://liquidinference.ai/connect/grok-4-fast)
- [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)