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xAI: Grok 4 Fast

x-ai/grok-4-fast

Created Sep 19, 20252,000,000 context
Starting at $0.20/M input tokensStarting at $0.50/M output tokens

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.

Reasoning can be enabled/disabled using the reasoning enabled parameter in the API. Learn more in our docs

Providers for Grok 4 Fast

OpenRouter routes requests to the best providers that are able to handle your prompt size and parameters, with fallbacks to maximize uptime.

Performance for Grok 4 Fast

Compare different providers across OpenRouter

Apps using Grok 4 Fast

Top public apps this month

Recent activity on Grok 4 Fast

Total usage per day on OpenRouter

Prompt
4.3B
Reasoning
509M
Completion
388M

Prompt tokens measure input size. Reasoning tokens show internal thinking before a response. Completion tokens reflect total output length.

Uptime stats for Grok 4 Fast

Uptime stats for Grok 4 Fast across all providers

Sample code and API for Grok 4 Fast

OpenRouter normalizes requests and responses across providers for you.

OpenRouter provides an OpenAI-compatible completion API to 400+ models & providers that you can call directly, or using the OpenAI SDK. Additionally, some third-party SDKs are available.

In the examples below, the OpenRouter-specific headers are optional. Setting them allows your app to appear on the OpenRouter leaderboards.

Using third-party SDKs

For information about using third-party SDKs and frameworks with OpenRouter, please see our frameworks documentation.

See the Request docs for all possible fields, and Parameters for explanations of specific sampling parameters.