Using Step 3.5 Flash on OpenRouter

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 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.

About OpenRouter

OpenRouter provides a unified interface for Large Language Models with better pricing, improved uptime, and no subscription requirements. Route across providers for cost optimization and reliability.

Multi-provider LLM aggregator offering unified API access to 300+ models from all major labs and emerging providers, with automatic failover for reliability.

Pricing on OpenRouter

Capabilities

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.