StepFun / stepfun/step-5-preview
Step 5 Preview - access through LLMTR
Step 5 Preview is the preview release of StepFun's flagship model for agentic work. It is suited to software development, professional knowledge work including finance, multi-step tool-using flows, and long-document analysis; its 1M-token context window holds several sources and a long conversation history in one request. It accepts text, image, and video input; video is sent as base64. It supports tool calling, JSON mode, and structured output with JSON Schema. reasoning_effort selects low, medium, or high; the model also reasons without the parameter, and reasoning tokens count as output and are drawn from the max_tokens budget. Repeated prompt prefixes can be billed at the discounted prompt cache rate.
Technical specifications
| Canonical ID | stepfun/step-5-preview |
|---|---|
| Provider | StepFun |
| Context window | 1,024,000 tokens |
| Operations | CHAT_COMPLETIONS |
| Modalities | text, image, video |
Pricing
An 8% platform margin applies to credit top-ups; model usage prices are not separately marked up.
| Operation | Metric | Unit | Price |
|---|---|---|---|
| CHAT_COMPLETIONS | INPUT_TEXT | PER_1M_TOKENS | $1.00 |
| CHAT_COMPLETIONS | CACHE_READ | PER_1M_TOKENS | $0.100000 |
| CHAT_COMPLETIONS | OUTPUT_TEXT | PER_1M_TOKENS | $2.70 |
Example usage
With existing OpenAI SDK flows, change only the base URL and model identifier.
curl https://llmtr.com/v1/chat/completions -H "Authorization: Bearer llmtr-your_key" -H "Content-Type: application/json" -d '{"model":"stepfun/step-5-preview","messages":[{"role":"user","content":"Hello"}]}'Guides about this model
- Step 5 Preview API: OpenAI-compatible access, 1M context and pricing - On LLMTR, StepFun Step 5 Preview is called as stepfun/step-5-preview at https://llmtr.com/v1/chat/completions. The context is 1,024,000 tokens; per 1M tokens, input costs $1.00, cached input $0.10 and output $2.70. reasoning_effort accepts low, medium and high.
- Video and image input with Step 5 Preview: an API request with base64 - stepfun/step-5-preview reads base64 video and images sent as video_url and image_url parts in a https://llmtr.com/v1/chat/completions request and returns a text answer. Base64 video is limited to about 9 MB, a message carries at most 16 parts, and media is billed as input tokens at $1.00 per 1M tokens.
- Step 5 Preview or Step 3.7 Flash? Context and cost for agent work - stepfun/step-5-preview has a 1,024,000-token context and costs $1.00 / $0.10 / $2.70, while stepfun/step-3.7-flash has a 256,000-token context and costs $0.20 / $0.04 / $1.15 (input / cached input / output per 1M tokens). Both are called with the same key at https://llmtr.com/v1/chat/completions; Step 5 Preview fits long context and json_schema, Step 3.7 Flash short, frequent turns.
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