Mystery solved: Z.ai revealed as maker of the buzzy Ox Alpha model
Chinese AI lab Z.ai has been confirmed as the creator of Ox Alpha, an anonymously released open-weight model that quickly climbed to the top of benchmark leaderboards over the weekend. The company said Ox Alpha is the latest entry in its GLM series and will release its weights on Wednesday.
Speculation ran high over the weekend as developers tried to figure out which AI company had quietly released Ox Alpha, an open-weight model that appeared anonymously on OpenRouter and rapidly rose to the top of multiple benchmark leaderboards, outperforming some of the industry's best-known models.
According to Bloomberg, the mystery has been resolved: the model comes from Z.ai, the lab behind the GLM model family. Z.ai confirmed that Ox Alpha is the newest version in its GLM lineup — the same series Hugging Face recently relied on to fend off an attempted attack from OpenAI-built agents.
Z.ai said it plans to release the weights for Ox Alpha on Wednesday, after which outside developers will be able to build applications on top of it. The company describes the model as a reasoning system built for coding, extended autonomous agentic work, and production-grade use cases, saying it is well suited to long-horizon software engineering tasks, complex reasoning problems, and workflows that mix text with visual inputs.
Rising pressure from Chinese labs
The launch adds to a growing pattern of low-cost, high-performing AI models coming out of China that threaten to erode the market position of pricier frontier labs such as OpenAI and Anthropic. Earlier this month, Z.ai also released GLM-5.3, a model that reportedly matches Anthropic's Fable 5 on some benchmark tests.
TechCrunch has reached out to Z.ai for further comment.
