GLM-5.3-Flash is 320B total, 18B active, MIT-licensed, and it's the model that was running as Ox Alpha.

Z.ai's model card gives the specifics: natively multimodal, 1M context, the first GLM model combining sparse and linear attention plus Manifold-Constrained Hyper-Connections, trained on a 30T-token multimodal corpus (Hugging Face). Z.ai claims it beats GLM-5.2 across benchmarks at one tenth the price and approaches Claude Opus 4.8 on coding and agentic work. Two settings will blow up your first bill if you miss them: reasoning_effort has low, high and max levels and defaults to max, and clear_thinking defaults to false and should be set true for chat.