Z.ai open-sources ‘Ox Alpha’ model as GLM-5.3-Flash
AI developer Z.ai has open-sourced the weights and code for GLM-5.3-Flash, a large language model previously introduced anonymously under the codename Ox Alpha. The model initially debuted as a free hosted service on the model marketplace OpenRouter before Z.ai revealed ownership. According to Z.ai, GLM-5.3-Flash provides up to a tenfold improvement in cost efficiency compared to its prior generation model, targeting developers seeking high-throughput, low-latency inference at reduced operational costs.