StepFun: Step 3.7 Flash

stepfun/step-3.7-flash

Modalities: text+image+video->text
In / out price: $0.2 / $1.15
Context: 262K
Released: May 28, 2026
Knowledge cutoff: —

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...

VisionVideoToolsReasoningStructured outputLong context

Supported parameters

frequency_penalty
Frequency penalty
Lowers the chance of a token in proportion to how often it already appeared.
include_reasoning
Include reasoning
Include a reasoning summary in the response.
logprobs
Logprobs
Return the log probability of each output token.
max_tokens
Max tokens
Upper bound on generated tokens. Output stops at the limit.
presence_penalty
Presence penalty
Lowers the chance of any token that has already appeared.
reasoning
Reasoning
Enable or configure reasoning. The fields differ by model.
reasoning_effort
Reasoning effort
How much compute to spend reasoning. Often low, medium, or high.
repetition_penalty
Repetition penalty
Penalizes text that already appeared. Common on open models.
response_format
Response format
For example json_object or json_schema, to constrain the shape.
seed
Seed
A fixed seed helps reproduce sampling. It does not guarantee byte-identical output.
stop
Stop
Stop when these strings are produced. A string or an array of strings.
structured_outputs
Structured outputs
Generate a parseable structure that follows a JSON Schema.
temperature
Temperature
Sampling temperature. Lower is steadier, higher is more varied. Often 0 to 2.
tool_choice
Tool choice
Whether to call a tool: auto, none, or a named function.
tools
Tools
Function definitions the model may call via tool_calls.
top_k
Top-K
Sample only from the K most likely tokens.
top_logprobs
Top logprobs
Also return the most likely alternatives at each position.
top_p
Top-p
Sample only from tokens whose cumulative probability reaches top_p.

Supported parameters

frequency_penalty

Frequency penalty

Lowers the chance of a token in proportion to how often it already appeared.

include_reasoning

Include reasoning

Include a reasoning summary in the response.

logprobs

Logprobs

Return the log probability of each output token.

max_tokens

Max tokens

Upper bound on generated tokens. Output stops at the limit.

presence_penalty

Presence penalty

Lowers the chance of any token that has already appeared.

reasoning

Reasoning

Enable or configure reasoning. The fields differ by model.

reasoning_effort

Reasoning effort

How much compute to spend reasoning. Often low, medium, or high.

repetition_penalty

Repetition penalty

Penalizes text that already appeared. Common on open models.

response_format

Response format

For example json_object or json_schema, to constrain the shape.

seed

Seed

A fixed seed helps reproduce sampling. It does not guarantee byte-identical output.

stop

Stop

Stop when these strings are produced. A string or an array of strings.

structured_outputs

Structured outputs

Generate a parseable structure that follows a JSON Schema.

temperature

Temperature

Sampling temperature. Lower is steadier, higher is more varied. Often 0 to 2.

tool_choice

Tool choice

Whether to call a tool: auto, none, or a named function.

tools

Tools

Function definitions the model may call via tool_calls.

top_k

Top-K

Sample only from the K most likely tokens.

top_logprobs

Top logprobs

Also return the most likely alternatives at each position.

top_p

Top-p

Sample only from tokens whose cumulative probability reaches top_p.