Chinese technology company Z.ai says it was behind the mysterious free AI model, Ox Alphathat generated buzz for his performance.
In a blog post published on Wednesday, Z.ai said Ox Alpha was an anonymous preview of its new GLM-5.3-Flash model, tested on OpenRouter and OpenCode to gather user feedback before release.
The company said it has made the model’s weights public available on the Cuddle Face platformallowing developers to download it, modify it and build on it.
Z.ai said the model is multimodal, meaning it can work with text, images and video, and has a context window of up to 1 million tokens.
Last week, Ox Alpha became the subject of intense online speculation after developers started testing it.
OpenRouter, a platform for accessing AI tools, described Ox Alpha as a reasoning model for coding, long-term agentic work, and production workloads.
Ox Alpha was also offered free for a week with “nearly unlimited use,” according to OpenCode, an open-source AI coding agent. OpenCode said the provider had a capacity of 100 trillion tokens per day.
The model received early praise from prominent tech figures. Stripe CEO Patrick Collison wrote on X that it was “very impressive.”
Bloomberg previously reported that Z.ai had confirmed it was behind Ox Alpha.
Some developers had already identified Z.ai as one of the leading capabilities. Wccftech, an online tech publication, reported similarities between the tokenizer behavior and responses of Ox Alpha and Z.ai’s GLM models.
The company had previously anonymously tested a GLM model under the name Pony Alpha.
The model’s name generated another possible clue. Chinese social media users linked ‘Ox’ to ‘Niu Lai’, which translates to ‘Here Comes the Ox’, a low-budget Chinese animated film that became a viral meme this summer. Users on Weibo started calling the AI model with the name of the movie and speculated that it had Chinese origins.
Some analysts suggested that technical signals could instead point to Microsoft’s MAI family, while Reddit users noted that Ox Alpha was willing to discuss politically sensitive topics that Chinese-made chatbots often avoid.
Z.ai did not immediately respond to Business Insider’s request for comment.
