Grok 4.1 Fast

xAI

Best tool-calling model with 2M context window. Optimized for speed, accuracy, and enterprise agentic workflows. Trained with long-horizon RL for consistent performance across full context. Available as grok-4-1-fast-reasoning and grok-4-1-fast-non-reasoning variants.

Text Generation API Grok Family
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Parameters
-
params
Context Window
2.0M
tokens
Max Output
-
tokens
Input Price
$0.2000
per 1M tokens
Output Price
$0.5000
per 1M tokens

Grok Family Timeline 8 versions

Grok 4.20 Beta Latest api
Mar 2026
Grok 4.1 Fast Current api
Nov 2025
Grok 4.1 api
Nov 2025
Grok Code Fast 1 api
Aug 2025
Grok 4 api
Jul 2025
Grok 3 Mini api
Mar 2025
Grok 3 api
Feb 2025
Grok 2 api
-

Capabilities

👁️
Vision
⚡
Function Calling
📋
JSON Mode
🌊
Streaming
💬
System Prompt
🖥️
Code Execution
🔍
Web Search
🔌
MCP Support

Extended Pricing

Input
$0.2000/1M
Output
$0.5000/1M
Cache Read
$0.7500/1M

Details

Release Date
November 19, 2025
Knowledge Cutoff
November 1, 2024
Source
API
API Key Required
Yes
License
Proprietary
Model ID
grok-4.1-fast
Last updated: March 13, 2026