AI Model APIs
AI Model APIsProviders
AI Model APIs

The complete platform for comparing AI models. Find pricing, capabilities, and the perfect model for your use case.

contact@aimodelapis.com

Resources

  • AI Models APIs
  • Providers

About

  • About
  • Contact
  • Privacy Policy
  • Terms of Service

© 2026 AI Model APIs. All rights reserved.

Back to Models
StepFun Step Plan (Global)

Step 3.5 Flash 2603 API

StepFun Step Plan (Global)
About

Build advanced reasoning agents with Step 3.5 Flash 2603, 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, open weights architecture. Access Step 3.5 Flash 2603 via the StepFun Step Plan (Global) API with up to 256K output tokens.

Capabilities

Input Modalities

text

Output Modalities

text
Reasoning
Yes
Structured Output
No
Tool Use
Yes
WeightsOpen
Temperature
Adjustable
Attachment
Not Supported
Limits
Context Window
256K

Tokens

Input Limit
256K

Tokens

Max Output
256K

Tokens

Pricing

Standard (per 1M tokens)

Input
Free
Output
Free
Frequently Asked Questions

Step 3.5 Flash 2603 by StepFun Step Plan (Global) costs Free per 1M input tokens and Free per 1M output tokens.

Model Details
ID
step-3.5-flash-2603
Provider
StepFun Step Plan (Global)
Family
Release Date
Apr 2, 2026
Knowledge Cutoff
Jan 1, 2025
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
STEPFUN_API_KEY
API Base URL
https://api.stepfun.ai/step_plan/v1
Documentation