StepFun Releases Step 5 Preview, a 600B Sparse MoE Model Targeting Agentic AI Work

StepFun has launched Step 5 Preview, a 600-billion-parameter sparse mixture-of-experts model designed for long-horizon agentic tasks, with a 1 million-token context window and broad multimodal support. The 27B-active-parameter model became available immediately via StepFun AI Studio and public APIs on September 20, with full model weights set for release on October 15.