Z.ai, formerly known as Zhipu AI, is a Chinese artificial intelligence company founded in 2019 from Tsinghua University, best known for its open-weights GLM (General Language Model) family of large language models. As one of China's "AI tiger" companies and the third-largest LLM player, it was blacklisted by the US Commerce Department in January 2025 over national security concerns. In January 2026, it made history as China's first major LLM company to go public, listing on the Hong Kong Stock Exchange and closing its first day at US$558 million. The company has embraced open-source, releasing its GLM models under the MIT License since July 2025, and has launched successive versions like GLM-4.5, GLM-4.6, and GLM-5, with GLM-5.1 arriving in March 2026. However, in late February 2026, its shares plunged 23% due to a severe compute resource shortage, leading to user complaints and a temporary halt on new signups. It also owns the research database AMiner and has worked to make its models compatible with domestic Chinese chips from Huawei and Cambricon.