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Grok 4.1 Fast Reasoning

Grok 4.1 Fast Reasoning is xAI's reasoning-enabled Grok 4.1 Fast model optimized for agentic operations. It combines structured chain-of-thought reasoning with speed-optimized inference and a context window of 1M tokens for complex agent workflows. Your use subject to xAI's Terms & Privacy Policies.

ReasoningFile InputVision (Image)Tool UseImplicit Caching
Use with AI GatewayView docs
index.ts
import { streamText } from 'ai'


const result = streamText({
  model: 'xai/grok-4.1-fast-reasoning',
  prompt: 'Why is the sky blue?'
})
OverviewAboutProvidersThroughputLatencyUptimeStatusSimilarFAQ

Providers

Route requests across multiple providers. Copy a provider slug to set your preference. Visit the docs for more info. Using a provider means you agree to their terms, listed under Legal.

Provider
Context
Max Output
Latency
Throughput
Input
Output
Cache
Web Search
Capabilities
ZDR
No Training
Release Date
Google Vertex AI
Legal:Terms•Privacy
1M1M
1.9s
145tps
$0.20/M
$0.50/M
Read:$0.05/M
Write:—
—
+2
11/19/2025