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Kilo Gateway

StepFun: Step 3.5 Flash (free) API

Kilo Gateway
About

Build advanced reasoning agents with StepFun: Step 3.5 Flash (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 3.5 Flash (free) via the Kilo Gateway API with up to 262K output tokens.

Capabilities

Input Modalities

text

Output Modalities

text
Reasoning
Yes
Structured Output
No
Tool Use
Yes
WeightsClosed
Temperature
Adjustable
Attachment
Not Supported
Limits
Context Window
262K

Tokens

Input Limit
262K

Tokens

Max Output
262K

Tokens

Pricing

Standard (per 1M tokens)

Input
Free
Output
Free
Frequently Asked Questions

StepFun: Step 3.5 Flash (free) by Kilo Gateway costs Free per 1M input tokens and Free per 1M output tokens.

Model Details
ID
stepfun/step-3.5-flash:free
Provider
Kilo Gateway
Family
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
Documentation