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xAI: Grok 4.1 Fast

x-ai/grok-4.1-fast

Released Nov 19, 20252,000,000 context

Grok 4.1 Fast is xAI's best agentic tool calling model that shines in real-world use cases like customer support and deep research. 2M context window.

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

Recent activity on Grok 4.1 Fast

Total usage per day on OpenRouter

Prompt
47.8B
Reasoning
2.79B
Completion
1.54B

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