Z.ai opens GLM-5.3-Flash: mystery model Ox Alpha revealed, MIT-licensed 320B MoE
On August 26 Z.ai released GLM-5.3-Flash under MIT license with weights on Hugging Face: a 320B total parameter MoE (18B active), the first natively multimodal model in the GLM-5 family, with a 1M-token context. It was the mysterious Ox Alpha running incognito on OpenRouter.