Model · Multimodal language model
Step 5 Preview
StepFun's Step 5 Preview, a reasoning-focused sparse-MoE model with 600B total and 27B active parameters, 1M context, and vision input, announced September 20, 2026, with weights scheduled to open on October 15, 2026.
- Developer
- StepFun
- Distribution
- Developer API
- Artifact licensing
- Proprietary access
- License scope
- Reviewed release artifacts and mandatory terms; not an assessment of training code or training data openness.
- Licenses
- Proprietary
- Boundary
- This record represents the Step 5 Preview release announced September 20, 2026, a distinct line from the reviewed Step 3.5 Flash and Step 3.7 Flash records. The scheduled weight release and the earlier Step 3.x lines are separate boundaries.
Risk statements
Not yet examined.
Open in the directory → Open official model page ↗
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