tech
Mystery solved: Chinese lab Z.ai says it’s behind the Ox Alpha model that wowed Silicon Valley
The free AI coding model sparked widespread interest among developers after appearing anonymously on OpenRouter.
TL;DR
- Z.ai, a Chinese AI company, confirmed it is behind the Ox Alpha model.
- Ox Alpha was an anonymous preview of Z.ai's new GLM-5.3-Flash model, tested on OpenRouter and OpenCode.
- The model's weights are publicly available on Hugging Face for developers to use and modify.
- Ox Alpha is multimodal (text, images, video) with a context window of up to 1 million tokens.
- The model received praise from figures like Stripe CEO Patrick Collison.
- Z.ai had previously tested a model anonymously under the name Pony Alpha.
- Speculation about Ox Alpha's origins included links to a Chinese animated film and comparisons to Microsoft's MAI family.