Comprehensive side-by-side LLM comparison
UI-TARS-2 supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
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.
ByteDance
UI-TARS-2, released by ByteDance in September 2025, is a major generational upgrade of the UI-TARS family of GUI interaction models, with enhanced capabilities across computer control, game environments, code generation, and tool use. It targets agentic workflows requiring robust multimodal understanding of graphical interfaces across diverse application domains.
5 months newer
UI-TARS-2
ByteDance
2025-09-04
Step-3.5-Flash
StepFun
2026-02-02
Available providers and their performance metrics
Step-3.5-Flash
UI-TARS-2
Step-3.5-Flash
UI-TARS-2