Step 5 Preview API

Step 5 Preview is an agentic model especially suited to software engineering, finance, long-document analysis, multimodal understanding, and tool-assisted research.

Modalities: Image, Text, VideoText
In / Out price: $1.06/$2.86per 1M
Context window: 1M tokens
Released: Oct 8, 2026

Step 5 Preview overview

Step 5 Preview by StepFun

Send text, image, or video input to the API and receive a text response, optionally streamed or formatted as structured JSON.

Step 5 Preview specs

Model ID: stepfun/step-5-preview
Developer: StepFun
Context window: 1,000,000 tokens
Max output: 64,000 tokens
Input: Image, Text, Video
Output: Text
API: OpenAI-compatible, base URL https://api.aimlapi.com/v1

What Is Step 5 Preview API?

Step 5 Preview is StepFun’s flagship model for agentic work, with stated strengths in software engineering, professional knowledge work, and finance.

It natively accepts text, image, and video input and can use tools and documents for multi-step tasks.

Technical Reference

Developer	StepFun
Model ID	stepfun/step-5-preview
Release Date	October 8, 2026
Context Window	1,000,000 tokens (~1M)
Max Output Tokens	64,000 tokens
Modalities	Image, Text, Video → Text
Capabilities	reasoning, streaming, structured (JSON schema) output, tool/function calling, vision

What Step 5 Preview Brings to the Table

Agentic work
StepFun describes Step 5 Preview as a flagship model for agentic work and says it can support tasks involving tool calls and continued progress toward a deliverable.

Multimodal input
The model natively supports text, image, and video input.

Reasoning controls
Step 5 Preview supports low, medium, and high reasoning effort levels.

Structured responses
The model supports JSON Mode and JSON Schema structured outputs.

Where Step 5 Preview Makes the Most Sense

Software engineering
StepFun identifies software engineering as one of the model’s areas of strength.

Professional knowledge work
The model is positioned for professional knowledge work, including tasks that require handling information and progressing toward a deliverable.

Finance
StepFun states that Step 5 Preview has particular strength in finance.

Multimodal analysis
The model can be used for analyzing images, charts, screenshots, and video content.

Use cases

Software development: locating problems from code, dependency information, and error logs; modifying code; and recommending tests.

Long-document processing: organizing multiple sources, extracting and summarizing information, and cross-checking details.

Research and analysis: using search, code-execution, or document tools to break down tasks and produce structured results.

Multimodal understanding: analyzing screenshots, charts, and videos, then presenting conclusions in a specified format.

Capabilities

Reasoning
Streaming
Structured outputs
Function calling
Vision

Step 5 Preview benchmarks by Artificial Analysis

See how Step 5 Preview compares in intelligence, generation speed, cost per task and latency. Data retrieved Nov 3, 2026.

Intelligence#24 / 5028.5Index v5.0 Speed#67 / 219143Output tokens / second Cost per task#30 / 44$2.35USD / benchmark task Latency#55 / 2160.92Seconds to first token

Intelligence

Index v5.0

Speed

Output tokens / second

Cost per task

USD / benchmark task

Benchmark results

Compare 12 models available on AI/ML API across 4 independent benchmarks.

Humanity's Last Exam

Expert-written questions across academic subjects.

Step 5 Preview API pricing

Step 5 Preview pricing in US dollars
Usage	Price	Unit
Input	$1.06	1M tokens
Output	$2.86	1M tokens
Cached input	$0.0529	1M tokens

Prices from the AI/ML API price list, checked on Nov 4, 2026.

Step 5 Preview vs other models: token prices

AI/ML API input and output rates for 5 models, per million tokens.

AI/ML API model prices in USD per million tokens
Model	Input	Output
Step 5 Preview	$1.06	$2.86
Step 3.7 Flash	$0.2116	$1.22
LongCat 2.0	$0.75	$2.95
Dola-Seed 2.0 Pro	$0.5	$3
Dola-Seed 2.0 Code	$0.5	$3

How to use the Step 5 Preview API

View docs

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key

export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/chat/completions' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "stepfun/step-5-preview",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the ocean."
    }
  ]
}'

import os
import requests

headers = {
    "Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
    "Content-Type": "application/json",
}
payload = {
    "model": "stepfun/step-5-preview",
    "messages": [
        {
            "role": "user",
            "content": "Write a haiku about the ocean."
        }
    ]
}

response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())

const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "stepfun/step-5-preview",
    "messages": [
      {
        "role": "user",
        "content": "Write a haiku about the ocean."
      }
    ]
  }),
});

if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());

Step 5 Preview FAQ

How much does Step 5 Preview cost?

Step 5 Preview costs $1.06 input and $2.86 output per 1M tokens on AI/ML API, billed as you go with no subscription.

What is Step 5 Preview designed for?

Step 5 Preview is StepFun’s flagship model for agentic work, with strengths in software engineering and professional knowledge work, particularly finance.

What input modalities does stepfun/step-5-preview support?

Step 5 Preview natively supports text, image, and video input.

Can Step 5 Preview analyze images and videos?

Yes. Step 5 Preview can understand images and videos without requiring an additional vision model.

Does Step 5 Preview support reasoning controls?

Yes. Step 5 Preview supports low, medium, and high reasoning effort levels.

Does Step 5 Preview support tool calling?

Yes. Tool calling is supported for Step 5 Preview.

Can Step 5 Preview return structured JSON?

Yes. Step 5 Preview supports both JSON Mode and JSON Schema structured outputs.

Does Step 5 Preview support streaming responses?

Yes. Streaming output is supported for Step 5 Preview.

What can Step 5 Preview do with multimodal inputs?

It can combine images, video, and text to extract and analyze multimodal information.

Is Step 5 Preview suitable for long-running agentic tasks?

Yes. It is intended for tasks involving large amounts of information, tool calls, and continuous progress toward a deliverable.

Start building with Step 5 Preview

Get API key

Step 5 Preview API

stepfun/step-5-preview

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key

export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/chat/completions' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "stepfun/step-5-preview",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the ocean."
    }
  ]
}'

import os
import requests

headers = {
    "Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
    "Content-Type": "application/json",
}
payload = {
    "model": "stepfun/step-5-preview",
    "messages": [
        {
            "role": "user",
            "content": "Write a haiku about the ocean."
        }
    ]
}

response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())

const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "stepfun/step-5-preview",
    "messages": [
      {
        "role": "user",
        "content": "Write a haiku about the ocean."
      }
    ]
  }),
});

if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());

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Step 5 Preview API

Step 5 Preview overview

Step 5 Preview by StepFun

Step 5 Preview specs

What Is Step 5 Preview API?

Technical Reference

What Step 5 Preview Brings to the Table

Where Step 5 Preview Makes the Most Sense

Use cases

Capabilities

Step 5 Preview benchmarks by Artificial Analysis

Intelligence

Speed

Cost per task

Benchmark results

Humanity's Last Exam

Terminal-Bench 4.0

AA-LCR

SciCode

Step 5 Preview API pricing

Step 5 Preview vs other models: token prices

How to use the Step 5 Preview API

Build with your agent

1Get your API key

2Make your first request

Step 5 Preview FAQ

Start building with Step 5 Preview

Step 5 Preview API

Build with your agent

1Get your API key

2Make your first request

Step 5 Preview API

Step 5 Preview overview

Step 5 Preview by StepFun

Step 5 Preview specs

What Is Step 5 Preview API?

Technical Reference

What Step 5 Preview Brings to the Table

Where Step 5 Preview Makes the Most Sense

Use cases

Capabilities

Intelligence

Speed

Cost per task

Benchmark results

Humanity's Last Exam

Terminal-Bench 4.0

AA-LCR

SciCode

Step 5 Preview API pricing

Step 5 Preview vs other models: token prices

How to use the Step 5 Preview API

Build with your agent

1Get your API key

2Make your first request

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