Step 3.5 Flash
Provider：StepFun
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....
Key specs
- Context：262.1K
- Max output：65.5K
- Tokenizer：Other
- Released：2026-01-29
Token pricing
- Input price：$0.100 / 1M tokens
- Output price：$0.300 / 1M tokens
- Blended price：$0.150 / 1M tokens
Modalities
Text
Use Cases
- Deep Reasoning & Analysis：Process long legal docs, academic papers, financial reports; multi-hop reasoning and evidence-chain tracing across huge contexts.（≈ $0.0024/call）
- Chat & Support：FAQ auto-response, multi-turn dialogue, emotion detection — e-commerce, finance, gov.（≈ $0.0015/turn）
When to pick this model
Signals derived from public pricing and spec fields — not a benchmark. Validate with official docs and your own eval.
- Low input + output price: solid fit for high-frequency calls and batch processing.
- Low blended price: budget-friendly for fleet-scale deployment.
- Long max output (>=30K tokens): strong fit for deep report / essay / document-drafting workflows.
FAQ
- What is the token pricing of Step 3.5 Flash? Input price $0.100 / 1M tokens, output price $0.300 / 1M tokens, blended about $0.150 / 1M tokens. Refer to StepFun’s official page for the exact rate.
- What context window does Step 3.5 Flash support? Context window is 262.1K, max output about 65.5K, suitable for long documents, multi-turn chat and complex reasoning.
- What scenarios is Step 3.5 Flash best for? Based on its capability and pricing, Step 3.5 Flash fits best: Deep Reasoning & Analysis, Chat & Support. See the Use Cases section for details and cost estimates.
- What input/output modalities does Step 3.5 Flash support? Supports Text modality.
- Is Step 3.5 Flash a free model? Step 3.5 Flash is billed per token, not a free model.
- Which provider offers Step 3.5 Flash? Step 3.5 Flash is offered by StepFun.
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Full info：Step 3.5 Flash