Step 5 Preview is StepFun’s flagship model for agentic work. It delivers frontier-level performance across software engineering and professional knowledge work, with particular strength in finance. It natively supports text, image, and video input and provides a 1M-token context window, making it suitable for tasks that require large amounts of information, tool calls, and continuous progress toward a deliverable.
At a glance
Core capabilities
Long-context understanding and reasoning
Analyze long documents, multiple source materials, and conversation history within a 1M-token context.Typical tasks: cross-document question answering and research material organization.
Programming and software engineering
Work across multiple programming languages and engineering tasks, with tools to advance development, modification, and verification.Typical tasks: troubleshooting, code changes, and test creation.
Multi-step Agent tasks
Use tools provided by an application to retrieve information, process documents, and continue through multi-step work.Typical tasks: deep research and analytical reporting.
Multimodal understanding
Combine images, video, and text to extract and analyze multimodal information.Typical tasks: chart analysis, screenshot question answering, and video summarization.
Use cases
- Software development: Combine code, dependency information, and error logs to locate problems, modify code, and recommend tests.
- Long-document processing: Organize multiple sources in a long context, extract and summarize information, and cross-check details.
- Research and analysis: Work with search, code execution, or document tools to break down tasks and produce structured results.
- Multimodal understanding: Analyze screenshots, charts, and video, and output conclusions in a specified format.
Input and output
Image and video input
See the Quickstart for image and video request examples. For complete limits, see Image understanding best practices and Video understanding best practices.
Features and configuration
Integration
- Create an API key on the StepFun Open Platform.
- Open the Quickstart, select Step 5 Preview, and switch between the text chat, image understanding, and video understanding examples.
- Send a request with cURL or Python and read the result from
choices[0].message.content. - Before going live, use the API reference to add timeout, retry, error-handling, and key-management logic.
Quickstart
See text, image, and video request examples.
Chat Completions API
See the complete request parameters, response fields, and usage information.
Claude Code integration
Configure Step Plan and enable 1M context.