StepFun: Step 3.5 Flash (free)
StepFun's Step 3.5 Flash free tier offers a generous 256K context window and tool use support, but without its own benchmark data it must be scored conservatively — refer to the paid version for verified performance figures.
Assessment date: March 12, 2026
Our methodology takes into account a range of factors including pricing, functionality, capabilities, benchmark performance, and real-world applicability. Rankings are reviewed and updated regularly as new models are released. Issues with our rankings? Contact us
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
Architecture
| Modality | Text → Text |
| Tokenizer | Other |
Model Information
Live Performance
Live endpoint metrics — refreshed every 30 minutes.
