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StepFun: Step 3.5 Flash

stepfun/step-3.5-flash
Jan 29, 2026256K context256K max output$0.10/M in · $0.30/M outReasoning

Description

Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token. It is a reasoning model that is incredibly speed efficient even at long contexts.

Specifications

Provider
stepfun
Context Length
256K
Max Output
256K
Modality
Intext
Outtext

Pricing

TypePrice / 1M tokens
Input$0.10
Output$0.30
Cache Read$0.02

Quick Start

curl https://api.ominigate.ai/v1/chat/completions \
  -H "Authorization: Bearer sk-omg-your-api-key" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "stepfun/step-3.5-flash",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'
StepFun: Step 3.5 Flash — Pricing & API on OminiGate