StepFun: Step 5 Preview (free) API
About
Build advanced reasoning agents with StepFun: Step 5 Preview (free), a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers available completely free of charge, native tool calling support. Access StepFun: Step 5 Preview (free) via the Kilo Gateway API with up to 64K output tokens.
Capabilities
Input Modalities
textimage
Output Modalities
text
Reasoning
Yes
Structured Output
Limits
Context Window
1.0M
Tokens
Input Limit
1.0M
Tokens
Max Output
64K
Tokens
Pricing
Standard (per 1M tokens)
Input
Free
Output
Free
Reasoning (per 1M tokens)
Output
Free
Caching (per 1M tokens)
Read
Free
Frequently Asked Questions
StepFun: Step 5 Preview (free) by Kilo Gateway costs Free per 1M input tokens and Free per 1M output tokens. Cached reads cost Free per 1M tokens.
Model Details
ID
stepfun/step-5-preview-free
Provider
Kilo GatewayFamily
step
Release Date
Aug 26, 2025
Knowledge Cutoff
N/A
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
KILO_API_KEY
API Base URL
https://api.kilo.ai/api/gateway