Step 5 Preview
StepFun · Step · closed weights
- MoE
Facts and where they come from
| Released | 2026-09 | labannouncementStep 5 Preview announcement |
|---|---|---|
| Licence | proprietary | labannouncementweights not published |
| Total parameters | 600B | labannouncementannouncement: 600B total parameters, with 27B active per token |
| Active parameters | 27B | labannouncementannouncement: 27B active per token |
| Context length | 1,000,000 tokens | labannouncementannouncement: supports a 1M-token context window |
| Mixture of experts | yes | labannouncementannouncement: a sparse Mixture-of-Experts architecture |
Architecture
not disclosed No diagram or modelled costs: weights not yet released (announced for 15 October 2026); no configuration published.
Sources
Listed in the LLM Architecture Gallery checklist as “Step-5 Preview (600B)” (name only; see about).