StepFun: Step 3.5 Flash

stepfun/step-3.5-flash

Modalities: text->text
In / out price: $0.1 / $0.3
Context: 262K
Released: Jan 29, 2026
Knowledge cutoff: —

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....

ToolsReasoningLong 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.
max_tokens
Max tokens
Upper bound on generated tokens. Output stops at the limit.
reasoning
Reasoning
Enable or configure reasoning. The fields differ by model.
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_p
Top-p
Sample only from tokens whose cumulative probability reaches top_p.

Models 阶跃星辰

StepFun: Step 3.5 Flash

stepfun/step-3.5-flash

Try this model

Modalities: text->text
In / out price: $0.1 / $0.3
Context: 262K
Released: Jan 29, 2026
Knowledge cutoff: —

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....

ToolsReasoningLong 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.
max_tokens
Max tokens
Upper bound on generated tokens. Output stops at the limit.
reasoning
Reasoning
Enable or configure reasoning. The fields differ by model.
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_p
Top-p
Sample only from tokens whose cumulative probability reaches top_p.