StepFun: Step 3.5 Flash (free) reasoning

openrouter
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 that is incredibly speed efficient even at long contexts.

Capabilities

Context Window 256k tokens
Max Output 256k tokens
Inputs
Outputs

Pricing (per 1M tokens)

Input $-
Output $-
Cache Read -
Cache Write -

Supported Parameters

frequency_penaltyinclude_reasoningmax_tokensreasoningstoptemperaturetoolstop_p

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