Gemini 2.5 Pro vs Step-3.5-Flash

Gemini 2.5 Pro

Google DeepMind

Gemini 2.5 Pro, released by Google in May 2025, is a large language model from the Gemini 2.5 family designed for complex reasoning, coding, and long-context analysis tasks. It features a 1M token context window, native support for text, image, video, and audio input, and integrated thinking capabilities for multi-step problem solving. Gemini 2.5 Pro targets advanced coding workflows, scientific reasoning, and applications requiring deep understanding across large, mixed-modality contexts.

StepFun

Step-3.5-Flash, released by StepFun on February 2, 2026, is a Mixture-of-Experts large language model with 197 billion total parameters and approximately 11 billion active parameters per inference. It features a 256K token context window using a 3:1 sliding-window-to-full-attention ratio, processing 100–350 tokens per second. Step-3.5-Flash targets agentic tasks, coding workflows, and open-source deployments requiring frontier reasoning capabilities with efficient inference, under an Apache 2.0 license.