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Step 3.5 Flash on OpenRouter

Step · StepFun

ServerlessOpen Source

Pricing

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

Capabilities

VisionMultimodalReasoningFunction CallingTool UseStructured OutputsCode Execution

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.

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Model Specs

Released2026-01-29
Parameters196B (11B active)
Context256K
ArchitectureMixture of Experts