StepFun: Step 3.5 Flash
stepfun/step-3.5-flash:free
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.
Modalities
Price
Free
Context
256K
Weekly Tokens
88.3B
Released
Jan 29, 2026