Step 3.7 Flash
by StepFunReleased May 28, 2026
stepfun/step-3.7-flash- Reads images
- Calls tools
- Answers in a JSON schema
- Reasons before it answers
Step 3.7 Flash is StepFun's latest high-efficiency multimodal Mixture-of-Experts model. It pairs a 196B-parameter language backbone with a vision encoder for native image and video understanding, activating roughly 11B parameters...
- Input / 1M tokens
- $0.24
- Output / 1M tokens
- $1.38
- Context
- 262K
- Longest answer
- 230K
What it costs
What each call is charged to the token's AI credit.
| Billed for | You pay |
|---|---|
| Input tokens | $0.24 / 1M |
| Output tokens | $1.38 / 1M |
| Cached input, read | $0.048 / 1M |
A typical call
A short chat turn: 2,000 tokens in, 500 out.
- per call
- $0.0012
- calls per $20
- 17K
What it can do
From its listing. The router passes every field through.
- Reads imagesYes
- Reads files and PDFsNo
- Hears audioNo
- Calls toolsYes
- Answers in a JSON schemaYes
- Reasons before it answersYes
- Searches the webNo
- Caches long promptsYes
- Draws imagesNo
Call it
Any router key works, in the format your SDK already speaks.
import OpenAI from "openai";const ai = new OpenAI({ baseURL: "https://relayfor.si/api/v1", apiKey: process.env.RELAYFOR_ROUTER_KEY,});const reply = await ai.chat.completions.create({ model: "stepfun/step-3.7-flash", messages: [{ role: "user", content: "Welcome the 1,000th holder in one line." }],});Specifications
What its maker and providers list for it.
- Reads
- Text, Images, and Video
- Writes
- Text
- Context
- 262,144 tokens
- Longest answer
- 230,400 tokens
- Reasoning effort
- low to high
- Intelligence index
- 19.5 (#100 of 220 rated)
- Released
- May 28, 2026
- Moderation
- None
Request fields
The fields its providers accept, passed through as you send them.
- frequency_penalty
- include_reasoning
- logprobs
- max_tokens
- presence_penalty
- reasoning
- reasoning_effort
- repetition_penalty
- response_format
- seed
- stop
- structured_outputs
- temperature
- tool_choice
- tools
- top_k
- top_logprobs
- top_p
Questions
How much does Step 3.7 Flash cost?
$0.24 per million input tokens and $1.38 per million output tokens, paid from the token's AI credit. A call of 2,000 tokens in and 500 out costs about $0.0012.
How do I call Step 3.7 Flash?
Make a router key for one of your tokens on the dashboard, point any OpenAI or Anthropic SDK at https://relayfor.si/api/v1 and send the model id stepfun/step-3.7-flash. The token's AI credit pays for each call.
How long a prompt can Step 3.7 Flash take?
Up to 262,144 tokens of context, and up to 230,400 tokens in one answer.
Are my prompts stored?
No. The RFS Router passes each call through and keeps only its token counts and cost, for the token's usage page.
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