Qwen3.5 397B-A17B is Alibaba's flagship open-weight language model, featuring 397 billion total parameters with 512 Mixture-of-Experts activating just 17 billion per token. Released in February 2026, it supports 201 languages and a 256K-token context window, with multi-token prediction for accelerated inference. The model delivers state-of-the-art performance across language understanding, logical reasoning, code generation, and GUI interactions, while being 60% cheaper to run than its predecessor and 8× more capable at handling large concurrent workloads.