StepFun
Step 5 Preview
StepFun's flagship preview for coding, research and professional analysis. A sparse 600B-parameter model activates 27B parameters per token.
Run this model
stepfun/step-5-preview
Use an endpoint supported by this model.
Get a key for this setup →const response = await fetch('https://api.minirouter.sh/v1/chat/completions', { method: 'POST', headers: { Authorization: `Bearer ${process.env.MINIROUTER_KEY}`, 'Content-Type': 'application/json', }, body: JSON.stringify({ model: 'stepfun/step-5-preview', messages: [{ role: 'user', content: 'Why is the sky blue?' }], max_tokens: 1024, }),}) const data = await response.json()console.log(data.choices[0].message.content)Use stepfun/step-5-preview with Chat Completions and an explicit max_tokens limit. Vercel currently lists max_tokens, temperature and stop; do not assume tools, tool_choice or configurable reasoning are supported. Generic client setup examples do not establish agent compatibility.
Model overview
- Input / 1M
- $1.05
- All-in MiniRouter rate
- Output / 1M
- $2.835
- All-in MiniRouter rate
- Context
- 1M
- 1,000,000 tokens
- Max output
- 1M
- tokens
- Architecture
- 600B MoE
- 27B active per token
- Open weights
- Planned Oct 15
- Publisher commitment, not released yet
- Announced
- 20 Sept 2026
- publisher release
Publisher evidence
Evaluate coding and professional work separately.
StepFun reports the following high-effort results. DeepSWE uses SWE-agent with temperature 1.0 and top_p 0.95. Each chart is a separate test; the percentages do not form a composite score or a MiniRouter performance claim.
StepFun-reported
DeepSWE v1.1
High-effort evaluation. Use the publisher's methodology when comparing with another model.
Step 5 Preview · high
0 to 100%
- Step 5 Preview67.7%
View chart data
| Model / effort | Reported result |
|---|---|
| Step 5 Preview / high | 67.7% |
StepFun-reported
Terminal-Bench 4.0
High-effort evaluation. Use the publisher's methodology when comparing with another model.
Step 5 Preview · high
0 to 100%
- Step 5 Preview33.3%
View chart data
| Model / effort | Reported result |
|---|---|
| Step 5 Preview / high | 33.3% |
StepFun-reported
FrontierFinance
High-effort evaluation. Use the publisher's methodology when comparing with another model.
Step 5 Preview · high
0 to 100%
- Step 5 Preview66.4%
View chart data
| Model / effort | Reported result |
|---|---|
| Step 5 Preview / high | 66.4% |
Trying the preview
Bring long source material and clear acceptance criteria.
The model's context and vision support make document-heavy tasks worth evaluating. Check the supported parameters before connecting an agent.
See the release and independent measurements- 01
Code and research
Try bounded code changes, document synthesis and evidence reconciliation. Keep tool execution in your application until the catalog advertises the tool parameters it needs.
- 02
Visual source material
Provide an image alongside a text question. The endpoint returns text; visual input does not imply image, video or audio generation.
- 03
Analytical reports
Verify calculations and source citations before relying on an analysis. Compare the quality and total tokens of a completed task, not just the output rate.
Costs and preview status
A context ceiling is not an output budget.
Vercel advertises 1M context and a 1M output ceiling. Input and generated output share that window; choose a smaller explicit output limit for your task.
Current provider listing- 01
Use the catalog price
MiniRouter's current prices appear above. Provider list prices and cache-read rates are documented separately in the release article; caching is not guaranteed for every request.
- 02
Keep the preview name
Select stepfun/step-5-preview explicitly. It is not an alias for Step 3.7 Flash, and an existing Flash configuration may send unsupported tool fields.
- 03
Open weights come later
StepFun plans an October 15 weight release. API access today does not establish a downloadable model, a license or self-hosting requirements.
One route, standard clients.
Authenticate with a MiniRouter bearer key. Caller-provided upstream credentials are not used on this route.
Read model setup docs →https://api.minirouter.sh/v1stepfun/step-5-preview/v1/chat/completions/v1/messages/v1/responsesmax_tokens, temperature, stop, reasoning, include_reasoning
Not enforced; a requested format is dropped and the answer is plain text.
Configured provider
Priority follows the live catalog order.
Input: text, image · Output: text
| Provider | Priority | Input / 1M | Output / 1M | Parameters | Access |
|---|---|---|---|---|---|
vercel | 1 | $1.05 | $2.835 | max_tokens, temperature, stop, reasoning, include_reasoning | MiniRouter balance |