StepFun: step-5-preview

About step-5-preview

StepFun Step 5 Preview — 600B-parameter sparse MoE flagship with 27B active parameters per token, 1M context, up to 64K output, native text/image/video understanding, always-on reasoning with low/medium/high effort, tool calling, structured output, streaming, and prompt caching.

Quickstart

Copy-paste API request.

curl -X POST https://api.chinaapi.ai/v1/chat/completions \
  -H "Authorization: Bearer $CHINAAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "step-5-preview",
    "messages": [
      {"role": "user", "content": "Summarize the main tradeoffs for this API workload."}
    ]
  }'

import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["CHINAAPI_API_KEY"],
    base_url="https://api.chinaapi.ai/v1",
)

response = client.chat.completions.create(
    model="step-5-preview",
    messages=[
        {"role": "user", "content": "Summarize the main tradeoffs for this API workload."}
    ],
)
print(response.choices[0].message.content)