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    • © 2025 OpenRouter, Inc

    xAI: Grok 4 Fast

    x-ai/grok-4-fast

    Created Sep 19, 20252,000,000 context

    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

    Recent activity on Grok 4 Fast

    Total usage per day on OpenRouter

    Prompt
    2.9B
    Reasoning
    287M
    Completion
    216M

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