Gemini 3 Flash vs Step-3.5-Flash

Gemini 3 Flash

Google DeepMind

Gemini 3 Flash, released by Google in December 2025, is a large language model from the Gemini 3 family that delivers reasoning and coding performance with efficiency optimized for high-volume workloads. It features a 1M token context window, 64K maximum output tokens, and native support for text, image, audio, video, and PDF input. Gemini 3 Flash targets cost-sensitive agentic workflows, document processing, and production APIs requiring fast, capable multimodal responses.

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.