stepfun/step-3.5-flash
Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token. It is a reasoning model...
Input⌘ / Ctrl + Enter
Try a prompt
OutputReady
Your response will appear here
Choose an example or write a prompt, then click Run.
API details and access
Model Details
ProviderStepfun
TypeLlm
Model IDstepfun/step-3.5-flash
Capabilities
InputText
OutputText
Context-
Max Output65,536
VisionNot supported
Function CallingSupported
Access details
Chat CompletionsBase URLhttps://api.sandbase.ai
API Endpoint/v1/chat/completions
{
"model": "stepfun/step-3.5-flash",
"messages": [
{
"role": "user",
"content": "Hello"
}
],
"max_tokens": 512
}Pricing
Input$0.10 / 1M tokens
Output$0.30 / 1M tokens
Production endpoint
Send your first request
OpenAI-compatible endpoint with unified authentication and usage tracking.
POST
https://api.sandbase.ai/v1/chat/completionsModel ID
stepfun/step-3.5-flash01
Input Schema
13 parameters · 1 required · 12 optional
| Parameter | Type | Required | Description |
|---|---|---|---|
messages | object[] | Required | — |
seed | integer | Optional | — |
stop | string[] | Optional | — |
tools | array | Optional | — |
top_k | integer | Optional | Min: 0 |
top_p | number | Optional | Min: 0 · Max: 1 |
stream | boolean | Optional | Default: false |
max_tokens | integer | Optional | Max: 65536 |
temperature | number | Optional | Min: 0 · Max: 2 · Default: 1 |
tool_choice | string | Optional | — |
response_format | object | Optional | — |
presence_penalty | number | Optional | Min: -2 · Max: 2 |
frequency_penalty | number | Optional | Min: -2 · Max: 2 |
02
Output Schema
| Field | Type | Description |
|---|---|---|
id | string | Unique identifier for the completion |
object | string | Object type, e.g. "chat.completion" |
model | string | Model used for the completion |
choices | array | List of completion choices |
choices[].message.content | string | Generated text content |
choices[].finish_reason | string | Reason the generation stopped |
usage.prompt_tokens | integer | Number of tokens in the prompt |
usage.completion_tokens | integer | Number of tokens in the completion |
usage.total_tokens | integer | Total tokens used |
03
Code Examples
Ready-to-run snippets
curl https://api.sandbase.ai/v1/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_API_KEY" \
-d '{
"model": "stepfun/step-3.5-flash",
"messages": [{"role": "user", "content": "Hello"}],
"temperature": 0.7,
"max_tokens": 2048,
"stream": true
}'