Claude Opus 4.6 vs Step-3.5-Flash

Claude Opus 4.6

Anthropic

Claude Opus 4.6, released by Anthropic in February 2026, is a large language model from the Claude 4 family designed for complex agent orchestration, extended reasoning, and long-form code generation. It features a 200K token context window (extendable to 1M tokens in beta), 128K maximum output tokens, native image understanding, and extended thinking with both standard and adaptive effort modes. Opus 4.6 targets multi-step agentic workflows, parallel tool use, and applications requiring sustained reasoning over large 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.