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....
StepFun: Step 3.5 Flash — StepFun. Context window 262,144 tokens. API pricing (per 1M tokens): Input $0.1, Output $0.3. License: Proprietary. LMArena 1,403.
| Provider | StepFun |
|---|---|
| API model ID | stepfun/step-3.5-flash |
| Tier | Frontier |
| Context window | 262,144 tokens |
| Max output | 65,536 tokens |
| License | Proprietary |
| API pricing (per 1M tokens) · Input | $0.1 |
| API pricing (per 1M tokens) · Output | $0.3 |
| LMArena | 1,403 (step-3.5-flash) |
LMArena (CC-BY 4.0, best reasoning setting, 2026-10-02) · GPQA Diamond: Epoch AI (CC-BY 4.0)
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