Is Grok 4 Fast available on FastMetal?

Not at the moment. Grok 4.5, from the same lab, is available on the FastMetal API today.

What is the context window of Grok 4 Fast?

2,000,000 tokens, shared between the prompt and the response.

How does Grok 4 Fast rank?

#101 on the public arena's Japanese board (ELO 1,370). Ranks move as the leaderboard is updated.

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x-ai/grok-4-fast

Not Available

Grok 4 Fast

Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model on xAI's [news post](http://x.ai/news/grok-4-fast). Reasoning can be enabled/disabled using the `reasoning` `enabled` parameter in the API. [Learn more in our docs](https://openrouter.ai/docs/use-cases/reasoning-tokens#controlling-reasoning-tokens)

9/19/2025

2,000,000 tokens

#101 Text (Japanese)

Specifications

Modalities

Input

text

image

Output

text

Supported Parameters

include_reasoning

logprobs

max_tokens

reasoning

response_format

seed

structured_outputs

temperature

tool_choice

tools

top_logprobs

top_p

Max Output Tokens

30,000

Frequently asked questions

Is Grok 4 Fast available on FastMetal?: Not at the moment. Grok 4.5, from the same lab, is available on the FastMetal API today.
What is the context window of Grok 4 Fast?: 2,000,000 tokens, shared between the prompt and the response.
How does Grok 4 Fast rank?: #101 on the public arena's Japanese board (ELO 1,370). Ranks move as the leaderboard is updated.