Step 5 Preview

Chat Completions

step-5-preview

StepFun|Created Oct 17, 2026|1.0M context

Chat Completions

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.

Overview Specifications Activity Performance Uptime Examples API Reference

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Pricing-50%

Pay-as-you-go rates for this model. More details in the billing guide.

Input Tokens (1M)

$0.50

Cached Input Tokens (1M)

$0.02

Output Tokens (1M)

$1.35

Capabilities

Input Modalities

TextImage

Output Modalities

Text

Supported Parameters

Available parameters for API requests

Frequency PenaltyLogprobsMax Completion TokensParallel Tool CallsPresence PenaltyReasoning EffortResponse FormatStopTemperatureTool ChoiceToolsTop PLogit Bias

Usage Analytics

Token usage of this model on our platform

Not enough activity data to display a chart

Throughput

Not enough throughput data

Time-To-First-Token (TTFT)

Not enough TTFT data

Code Example

Example code for using this model through our API with Python (OpenAI SDK) or cURL. Replace placeholders with your API key and model ID.

Basic request example. Ensure API key permissions. For more details, see our documentation.

from openai import OpenAI

client = OpenAI(
    base_url="https://api.naga.ac/v1",
    api_key="YOUR_API_KEY",
)

resp = client.chat.completions.create(
    model="step-5-preview",
    messages=[
        {"role": "user", "content": "What's 2+2?"}
    ],
    temperature=0.2,
)
print(resp.choices[0].message.content)