Z.ai Revealed as Maker of Mystery Benchmark-Topping Model Ox Alpha

Z.ai confirmed it built Ox Alpha, a reasoning model launched anonymously on OpenRouter that topped benchmarks with no attribution. A Bloomberg report surfaced the lab's involvement, after which Z.ai formally claimed the model — the newest iteration of its GLM series. Z.ai plans to release the model's open weights on Wednesday. Parameter count and licensing terms remain undisclosed.