Seed-1.8 vs Step-3.5-Flash

ByteDance

Seed-1.8, developed by ByteDance Seed, is a generalized agentic large language model supporting text and image input, with industry-leading GUI agent capabilities and improvements in multimodal reasoning over its predecessor Seed1.5-VL. It targets information retrieval, code generation, GUI interaction, and complex agentic workflows requiring robust multimodal understanding.

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.