StepFun is a Shanghai-based AI company founded in April 2023 by Jiang Daxin, Zhu Yibo and Jiao Binxing. It develops the Step series of language and multimodal models, including Step 3.5 Flash.
- Founded
- 2023
- Type
- Private company
- Founders
- Jiang Daxin, Zhu Yibo and Jiao Binxing
- AI lab
- Inference provider
- 3 hosted endpoints
Catalogue
All models by StepFun
4 models · 1–4
| Select models to compare | Model | Released | Context | Input /M | Output /M | Parameters | Type | I/O | Openness |
|---|---|---|---|---|---|---|---|---|---|
 Step 5 PreviewStepFun | September 16, 2026 | 1M | $1.00 | $2.70 | 604B | Text | text, image, video → text | Closed | |
| Step 3.7 FlashStepFun | May 29, 2026 | 262K | $0.20 | $1.15 | 201B | Text | text, image, video → text | Open weights | |
| Step 3.5 Flash 2603StepFun | April 2, 2026 | 256K | — | — | — | Text | text → text | Open weights | |
| Step 3.5 FlashStepFun | January 29, 2026 | 262K | $0.10 | $0.30 | 199B | Text | text → text | Open weights |