GLM-5.3 Flash is the official identity behind the heavily used Ox Alpha preview.
Z.ai describes a natively multimodal 320B-A18B model with a one-million-token context window under the MIT license. The release also turns a mystery-model experiment into a deployable model available through multiple gateways and coding tools.
This is an update, not a replay of Ox Alpha availability. The new information is the model identity, architecture, license, pricing, and announced weight release. Independent evaluation still matters because provider benchmark comparisons and early traffic are not substitutes for repeatable task-level results.