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.

ChatStepfun1M tokens$1.0901 / $2.9432 · 1M

stepfun/step-5-preview

Context
1M tokens
Completion cap
64,000
Tools
Yes
JSON
Yes
Released
2026-10-08

Call it from Geek Hub

Same OpenAI SDK. Change the base URL and the model id.

curl https://api.geekhub.mx/v1/chat/completions \
  -H "Authorization: Bearer $GEEKHUB_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "stepfun/step-5-preview",
    "messages": [{"role": "user", "content": "Hola"}]
  }'
Get an API key

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 runs on the Geek Hub API (OpenAI-compatible). Model id: stepfun/step-5-preview.
Is Step 5 Preview free?
No. Input is $1.0901 per 1M tokens and output is $2.9432 per 1M tokens on Geek Hub (markup included).
What is the context length of Step 5 Preview?
Step 5 Preview has a 1M tokens context window. It supports up to 64,000 completion tokens.
Does Step 5 Preview support tool calling and structured outputs?
Step 5 Preview accepts tools and tool_choice for function calling. It also supports structured outputs via a JSON schema in response_format.
When was Step 5 Preview released?
Step 5 Preview was released on 2026-10-08.

More models from Stepfun