Step 3.5 Flash 2603
StepFun · 196.8B parameters
Step 3.5 Flash 2603 is a 2026 efficiency update to StepFun's Step 3.5 Flash reasoning model. It introduces a configurable token-budget system with a low mode that uses significantly fewer tokens for straightforward requests and a high mode that preserves full reasoning depth, making it better suited for agentic workflows that issue many sequential tool calls.