Grok 4 Fast

December 17, 2025

TL;DR

Grok 4 Fast is a cost-efficient AI model that delivers frontier-level performance.
It achieves this through exceptional token efficiency, using 40% fewer thinking tokens than Grok 4 for similar benchmark results.
The model boasts a 2M token context window and a unified architecture that handles both reasoning and non-reasoning tasks.
Grok 4 Fast demonstrates advanced web and X search capabilities, integrating real-time data into its responses.
It has achieved a top ranking on LMArena's Search Arena and a strong performance on its Text Arena.
Grok 4 Fast is now available to all users, including free users, with a limited-time availability on OpenRouter and Vercel AI Gateway.
The model is offered in two versions: `grok-4-fast-reasoning` and `grok-4-fast-non-reasoning`, with specific pricing via the xAI API.

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