xAI: Grok 4 Fast Reasoning API
About
Build advanced reasoning agents with xAI: Grok 4 Fast Reasoning, 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 xAI: Grok 4 Fast Reasoning via the Helicone API with up to 2.0M output tokens.
Capabilities
Input Modalities
textimage
Output Modalities
text
Reasoning
Yes
Structured Output
Limits
Context Window
2.0M
Tokens
Input Limit
2.0M
Tokens
Max Output
2.0M
Tokens
Pricing
Standard (per 1M tokens)
Input
$0.20
Output
$0.50
Caching (per 1M tokens)
Read
$0.05
Frequently Asked Questions
xAI: Grok 4 Fast Reasoning by Helicone 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
grok-4-fast-reasoning
Provider
HeliconeFamily
grok
Release Date
Sep 1, 2025
Knowledge Cutoff
Sep 1, 2025
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
HELICONE_API_KEY
API Base URL
https://ai-gateway.helicone.ai/v1