Everything we know about Z.ai, the Chinese company behind the mysterious Ox Alpha model

Z.ai chairman and cofounder Liu Debing marks the company's debut on the Hong Kong Stock Exchange in January 2026.

Lam Yik/Bloomberg/Getty Images Chinese tech firm Z.ai revealed that mystery AI model Ox Alpha was actually its new GLM-5.3-Flash model.

The Tsinghua University spinout went public in Hong Kong in January and its shares have since surged.

Z.ai says all traffic from the Ox Alpha test ran on Chinese AI chips despite US technology restrictions.

For days, one of the most popular AI models of the week had no known maker.

Ox Alpha was free to try, impressive at coding, and mysterious enough to set developers guessing about which major AI lab was behind it.

Then Z.ai revealed itself.

The Beijing AI company said this week that Ox Alpha was the name it had used to anonymously test GLM-5.3-Flash, its latest open-weight model, on OpenRouter and OpenCode.

The stunt has put the newly public company in the spotlight as China's AI race heats up.

Z.ai is up against DeepSeek, Moonshot AI — the company behind Kimi — and Alibaba's Qwen team.

They're competing on performance and price, while trying to make the most of limited computing power.

Here's what to know.

Z.ai grew out of a top Chinese university Z.ai, also known in China as Zhipu AI, says it was founded in 2019 based on technology developed at Tsinghua University in Beijing.

The company developed GLM, short for General Language Model, its family of large language models.