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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 2M tokens for complex agent workflows.

ReasoningTool UseImplicit Cachingtiered-costVision (Image)File InputWeb Search
index.ts
import { streamText } from 'ai'


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

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Provider
Context
Latency
Throughput
Input
Output
Cache
Web Search
Per Query
Capabilities
ZDR
No Training
Release Date
xAI
Legal:Terms
•
Privacy
2M
6.5s
155tps
$0.20/M
$0.50/M
Read:
$0.05/M
Write:
—
$5/K
+ input costs
—
07/09/2025
Google Vertex
Legal:Terms
•
Privacy
1M
0.6s
$0.20/M$0.50/M
Read:$0.05/M
Write:—
——
07/09/2025