Zhipu, also known as Z.ai or ZhuFu AI, formally launched and open-sourced GLM-5.3-Flash after confirming that the anonymously tested Ox-Alpha model was a free preview of the system. Available on Hugging Face under an MIT license, the model has 320 billion total parameters and activates 18 billion at a time, natively accepting text, image and video inputs as the first natively multimodal model in the GLM-5 series. Ox-Alpha appeared on OpenRouter and OpenCode on Aug. 20 and, during a free week through Aug. 26, recorded 343.49 million calls and 27.2493 trillion tokens to rank first in usage, with all traffic served on Chinese AI chips. Artificial Analysis scored GLM-5.3 Flash at 57 on its overall intelligence index, ranking it eighth and matching OpenAI's GPT-5.6 Terra at input and output prices of $0.15 and $0.5 per million tokens. Stripe CEO Patrick Collison called the model "very impressive," while a Weibo hashtag about Z.ai claiming Ox Alpha drew thousands of posts, ranked among the platform's top 20 hot topics and was viewed more than 13 million times in under 24 hours.