Step-5-Preview

apache-2.0

Step 5 Preview is StepFun's flagship model for agentic work. It is a sparse Mixture-of-Experts model with 600B total parameters and 27B active per token, a 1M-token context window, and text and image input. It delivers frontier-level performance in software engineering, long-horizon agentic execution with repeated tool calls, and professional knowledge work, with particular strength in finance.

Context
1.0M
Input price
$1/1M tokens
Output price
$2.7/1M tokens

Capabilities

Reasoning & Interaction
Reasoning
Tool Calling
Output Control
Structured Output
JSON Mode
Infrastructure
Streaming
Fine-tuning

Details

Model IDstepfun-ai/Step-5-Preview
Provider DeepInfra
Creator StepFun
Family—
Licenseapache-2.0
Statusactive
Typechat
Input modalitiestext, image
Output modalitiestext
Open weightYes
Parameters—
Architecture—
Context window1.0M tokens
Max input—
Max output—
Reasoning tokensYes
Knowledge cutoff—
Release date—
Sourceofficial

Tools

Function Callingfunction_calling
Call external functions and APIs

Endpoints

Chat CompletionsPOST
Generate chat responses with messageshttps://api.deepinfra.com/v1/openai/v1/chat/completions

Pricing

Input
$1
Output
$2.7
Cache write
—
Cache read
$0.1
Batch in
—
Batch out
—

API

GET/v1/models/deepinfra/stepfun-ai/Step-5-Preview