StepFun: Step 3.5 Flash
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....
Everything else
| Max output | 66K |
|---|---|
| Input / 1M | $0.1 |
| Output / 1M | $0.3 |
| Cache read / 1M | — |
| Cache write / 1M | — |
| 1M in + 1M out | $0.4 |
| Takes | text |
| Returns | text |
| Tools | yes |
| Reasoning | always on |
| Open weights | yes |
| Released | 2026-01-29 |
| Knowledge cutoff | — |
| Retires | — |
| Catalog id | stepfun/step-3.5-flash |
Using it
In 00, this model is picked per agent — and per tier, so the model that answers your customers need not be the one that writes your code. Get 00.