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

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

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 300+ 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.