Grok 4.1 Fast API
About
Build advanced reasoning agents with Grok 4.1 Fast, a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers cost-effective pricing at $0.20/1M input and $0.50/1M output tokens, native tool calling support. Access Grok 4.1 Fast via the OpenRouter API with up to 30K output tokens.
Capabilities
Input Modalities
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Output Modalities
text
Reasoning
Yes
Structured Output
Yes
Tool Use
Yes
WeightsClosed
Temperature
Adjustable
Attachment
Supported
Limits
Context Window
2.0M
Tokens
Input Limit
2.0M
Tokens
Max Output
30K
Tokens
Pricing
Standard (per 1M tokens)
Input
$0.20
Output
$0.50
Caching (per 1M tokens)
Read
$0.05
Frequently Asked Questions
Grok 4.1 Fast by OpenRouter costs $0.20 per 1M input tokens and $0.50 per 1M output tokens. Cached reads cost $0.05 per 1M tokens.
Model Details
ID
x-ai/grok-4.1-fast
Provider
OpenRouterFamily
grok
Release Date
Nov 19, 2025
Knowledge Cutoff
Nov 1, 2024
API Integration
NPM Package
@openrouter/ai-sdk-provider
Environment Variables
OPENROUTER_API_KEY
API Base URL
https://openrouter.ai/api/v1