S
StepFun: step-5-preview:free
step-5-preview:free
1M context64K outReasoningToolsVisionVideoCacheStructured
Released Oct 8, 2026Updated Oct 10, 2026
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. It is designed for extended tasks that span large codebases and documents, using tools and refining results over multiple steps.
Tokenizer OtherQuantization fp8
Pricing
Input price
$0.00/ 1M tokens
Output price
$0.00/ 1M tokens
Compatible endpoints openaiVendor StepFun
Uptime
Performance
Loading performance data...
Usage & Ranking
Loading usage...
Supported parameters
All providers = every upstream serving this model supports it. Some providers = depends on which upstream handles the request. Default = the value sent when you leave the parameter unset.
| Parameter | Providers | Default |
|---|---|---|
| frequency_penalty | All providers | Not sent by default |
| include_reasoning | All providers | - |
| logprobs | All providers | - |
| max_tokens | All providers | - |
| presence_penalty | Some providers | Not sent by default |
| reasoning | All providers | - |
| reasoning_effort | All providers | - |
| repetition_penalty | Some providers | Not sent by default |
| response_format | All providers | - |
| stop | All providers | - |
| structured_outputs | All providers | - |
| temperature | All providers | Not sent by default |
| tools | All providers | - |
| top_k | Some providers | Not sent by default |
| top_logprobs | All providers | - |
| top_p | All providers | Not sent by default |