Ox Alpha was GLM-5.3-Flash the whole time. Z.ai just dropped the MIT weights.
Z.ai released GLM-5.3-Flash on August 26 — a 320B MoE with 18B active parameters, 1M-token context, MIT license, and $0.075/M input at a 50% launch discount. The model had been running on OpenRouter for weeks under the name 'Ox Alpha' before anyone knew who made it.