Step-3.5-Flash

Step 3.5 Flash is StepFun's most capable open-source foundation model, built on a sparse Mixture of Experts (MoE) architecture with 196B total parameters and only 11B activated per token. It supports a 262K context window and achieves 100-300 tok/s generation throughput via 3-way Multi-Token Prediction (MTP-3). The model excels at coding and agentic tasks, achieving 74.4% on SWE-bench Verified and 51.0% on Terminal-Bench 2.0