StepFun has open-sourced Step-3.5-Flash: 196 B total parameters, 11 B active, 256 K context length. Strong performance, with speed as the highlight—blazing fast, peaking at 350 tokens/s. It’s currently in promotion and free on OpenRouter `step-3.5-flash:free`.

More detials: https://static.stepfun.com/blog/step-3.5-flash/