GLM-5.3-Flash: The 320B Open-Weight Model That Ran on Chinese Chips
Z.ai spent six days serving an anonymous model called Ox Alpha on OpenRouter, took nearly 20% of the platform’s weekly token share, and only then revealed it was GLM-5.3-Flash — a 320B mixture-of-experts model with 18B active parameters, a one-million-token context window and MIT-licensed weights. This piece works through the hybrid attention architecture, what the benchmark table supports and what it does not, what the API actually costs once the launch promotion ends, how credible the domestic-silicon claim is, and what any of it changes for a business choosing a model this quarter.