Step 5 Preview, a 1M-context MoE from StepFun, shows up on OpenRouter

Reasoning effortAll3 days

Uptime (3d)The model was reachable. Request routed to a provider.

99.94%

Availability (3d)The model returned inference from any provider. Errors and empty responses count against it.

99.43%

Availability over the last 3 days

Last 72 hours

Availability 99.43%

3 Days Ago2 Days AgoYesterdayNow

Availability over the last 24 hours

OpenRouter Availability

99.74%

When an error occurs in an upstream provider, we can recover by routing to another healthy provider, if your request filters allow it. You can access per-provider uptime data programmatically through the Endpoints API. Learn more about our load balancing and customization options.

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Frequently asked questions

What is Step 5 Preview?

Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters). It performs strongly in software engineering and professional knowledge work, with particular strength in finance. It is designed for extended tasks that span large codebases and documents, using tools and refining results over multiple steps.

Step 5 Preview costs $1.00/M input tokens and $2.70/M output tokens, with separate rates for Cache Read at $0.05/M tokens.

Step 5 Preview has a 1,000,000 token context window. It supports up to 64,000 completion tokens.

Yes. Step 5 Preview accepts tools for function calling. It also supports structured outputs via a JSON schema in response_format.

Step 5 Preview accepts text, images, and video as input and returns text.

Step 3.7 Flash and Step 3.5 Flash are other text models from StepFun.

Step 5 Preview was released on October 8, 2026.