LLM Reference
OpenRouter

Using Step 3.5 Flash on OpenRouter

Implementation guide · Step · StepFun

Serverless

OpenRouter exposes Step 3.5 Flash through model ID stepfun/step-3.5-flash. Use the setup steps, sourced pricing, capabilities, and official provider links below to validate this route before deployment.

Last refreshed 2026-06-29. Next refresh: weekly.

Quick Start

  1. 1
    Create an account at OpenRouter and generate an API key.
  2. 2
    Use the OpenRouter SDK or REST API to call stepfun/step-3.5-flash — see the documentation for request format.
  3. 3
    You'll be billed $0.10/1M input, $0.30/1M output tokens. See full pricing.
API PortalDocumentationPricingModel Card

Code Examples

See OpenRouter documentation for integration details.

Pricing on OpenRouter

TypePrice (per 1M)
Input tokens$0.10
Output tokens$0.30

Capabilities

Reasoning

About Step 3.5 Flash

Step 3.5 Flash is StepFun's most capable open-source foundation model. Its sparse Mixture of Experts architecture activates only 11B of 196B total parameters per token, making it highly efficient at long contexts. Achieves 60.47% on SWE-Bench Verified and 56.2% on SWE-Pro, competing with frontier closed models on agentic coding benchmarks. Supports 256K token context.

Full model details →

Model Specs

Released2026-01-29
Parameters196B (11B active)
Context256k
ArchitectureMixture of Experts

More Models on OpenRouter

Step 3.7 Flash
All models on OpenRouter →

Provider

OpenRouter
OpenRouter

OpenRouter, Inc.

New York, NY, USA