On request, licence permitting
Step API:
StepFun’s flagship for agents and finance.
Step 5 Preview is built for long agentic tasks and does particularly well on finance work. Its licence is free for most uses but adds conditions for larger model-as-a-service businesses, so whether we can offer it depends on those terms. Tell us what you need it for.
What StepFun built it for
Long tasks, long documents, numbers
Repeated tool calls
Tasks that need many rounds of calling tools, checking results and revising, with long-context information carried throughout.
Documents and charts
Reads long documents, charts, screenshots and images, then produces structured reports and analyses.
Finance
StepFun singles out finance tasks that combine quantitative reasoning with financial data and supporting documents.
Model facts
Step 5 Preview specifications
| Architecture | Sparse Mixture-of-Experts: 600B total, 27B active |
| Context window | Up to 1M tokens Model maker’s figure |
| Maximum output | Up to 1M tokens Model maker’s figure |
| Input | Text and images |
| Licence | StepFun Model License 1.0 |
Source: StepFun’s Step 5 Preview model card and licence, checked 23 October 2026. This is a summary, not legal advice. Step, StepFun and the StepFun logo are trademarks of StepFun, shown only to identify the model. Their use does not imply endorsement.
Step API questions
Is Step 5 free for commercial use?
For most organisations, yes: the StepFun Model License 1.0 is royalty-free. Two cases need a separate commercial licence from StepFun: device makers building it into hardware, and model-as-a-service businesses whose group revenue tops US$20M over twelve months. Products above 100 million monthly users or US$20M monthly revenue must also show “Powered by StepFun AI”.
Can you add Step 5 to the Model API?
Possibly. Because offering it through an API is a model-as-a-service use, it depends on StepFun’s licence terms for providers. Talk to us about your use case and we’ll confirm.
How popular is Step 5 Preview?
On OpenRouter’s public rankings for the 30 days to 22 October 2026, Step 5 Preview was the ninth most-used model by tokens processed.
What can I use today?
The Model API’s standard models, with public per-token pricing, are Kimi K3 and DeepSeek V4.1 Flash.
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