xAI Corp.
grok-4-fast
xAI's latest advancement in cost-efficient reasoning models
🔧Tool calling⚡Caching
Pricing per 1M tokens
Input
$0.20
Output
$0.50
Cache write
$0.20
Cache read
$0.05
Specifications
Context window2M tokens
Max outputUnlimited
API typechat
AddedOct 16, 2025
Model IDxai/grok-4-fast
Privacy & data
Data retentionYes (30 days)
Used for trainingUnknown
Provider location🇺🇸 US
Privacy policyxAI Privacy Policy →