Step 3.5 Flash

Step 3.5 Flash is a lightweight language model from StepFun with a 262K token context window, designed for fast inference on tasks that don't require the full capacity of larger models.

Strengths

It offers fast inference speeds and reasonable performance for standard language tasks while maintaining a long context window for handling larger documents and conversations.

Best for

Applications prioritizing latency and throughput over maximum reasoning capability, such as real-time chat, content summarization, and document processing within a single request.

Limitations

It is superseded by Step 3.7 Flash (released May 2026), which uses sparse Mixture of Experts architecture for improved performance; Step 3.5 Flash is the older generation model and has lower capability across reasoning and complex tasks.