MODELS
by StepFun
Open sparse MoE reasoning model from StepFun with 196B total parameters, 11B active parameters, 256K context, and support for coding, tool use, agentic workflows, deep research, API access, and local deployment.
Step 3.5 Flash is StepFun’s open sparse MoE reasoning model. The official launch page describes it as a 196B-parameter model with 11B active parameters and a 256K context window, built for high-speed reasoning, coding, agentic intelligence, tool use, deep research, and local deployment. StepFun documentation lists it for API usage as model "step-3.5-flash" through the Chat Completion endpoint, and source pages also reference availability through GitHub and Hugging Face.
Use when you need an open MoE reasoning model with documented coding tool-use agentic and deep-research capabilities. Use when evaluating models that can be accessed through StepFun’s API while also being available from GitHub and Hugging Face. Use when a long-context model is needed and the officially stated 256K context window fits the task.
Last updated Jul 31, 2026