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Grok 3 Fast Beta

Grok 3 Fast Beta is the speed-optimized variant of xAI's Grok 3 model. It delivers lower latency inference while keeping the same Grok 3 training foundation, with a context window of 131.1K tokens.

Tool Use
index.ts
import { streamText } from 'ai'


const result = streamText({
  model: 'xai/grok-3-fast',
  prompt: 'Why is the sky blue?'
})
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Frequently Asked Questions

  • How much faster is Grok 3 Fast Beta compared to Grok 3?

    Grok 3 Fast Beta is optimized for lower latency inference. The exact speed improvement depends on prompt complexity and output length, but it's designed for interactive use cases where the full Grok 3 may feel too slow.

  • Does Grok 3 Fast Beta have the same context window as Grok 3?

    Yes, both share a context window of 131.1K tokens.

  • When should I choose Grok 3 Fast Beta over Grok 3 Mini?

    Grok 3 Fast Beta retains more of the full Grok 3 reasoning capability, while Grok 3 Mini is a smaller, more cost-efficient model. Choose Grok 3 Fast Beta when task quality is important but you also need low latency.

  • What does Grok 3 Fast Beta cost?

    This page lists the current rates. Multiple providers can serve Grok 3 Fast Beta, so AI Gateway surfaces live pricing rather than a single fixed figure.

  • How do I authenticate with Grok 3 Fast Beta through Vercel AI Gateway?

    Use your Vercel AI Gateway API key with xai/grok-3-fast as the model identifier. No separate xAI account is needed for gateway-managed access.

  • Is Grok 3 Fast Beta suitable for streaming responses?

    Yes. Grok 3 Fast Beta's speed optimization makes it well-suited for streaming responses in chat interfaces and real-time applications.

  • Does Vercel AI Gateway support Zero Data Retention for Grok 3 Fast Beta?

    Zero Data Retention is not currently available for this model. ZDR on AI Gateway applies to direct gateway requests; BYOK flows aren't covered. See https://vercel.com/docs/ai-gateway/capabilities/zdr for details.