StepFun · Open Weight Release

Step 5 Preview

Since Week 40 2026: StepFun has released the weights of its agentic flagship, which was previously only on its API. The 600B-total, 27B-active sparse mixture-of-experts model with up to 1M tokens of context is now on Hugging Face and ModelScope, ungated, as FP8, BF16 and NVFP4 checkpoints, with the release landing around 15 October. It uses a new StepFun Model License 1.0 in the Apache style that requires Powered by StepFun AI attribution above 100M monthly users or US$20M revenue and a separate commercial licence for hardware makers and large model-as-a-service businesses. The current model card lists text and image input; StepFun's own benchmarks focus on coding, agentic work, knowledge work and finance.