Ox Alpha arrived with the kind of performance claim that makes developers stop scrolling—and the kind of anonymity that turns a model launch into a guessing game. The free coding system is winning admirers, but nobody has established who is operating it.

The mystery began Thursday, when Ox Alpha appeared on OpenRouter as a “stealth model” from an anonymous third-party provider. It was pitched for coding, sustained agentic work, production workloads and long-horizon software engineering; OpenCode said it would offer near-unlimited free use for a week and cited capacity of 100 trillion tokens a day. Stripe chief executive Patrick Collison tested it and called it “very impressive.”¹

By Friday, the strongest public theory pointed to China’s Z.ai, the company behind the GLM model family. The case was circumstantial but specific: observers noted apparent similarities in tokenizer behavior and responses, while Z.ai had previously tested GLM-5 anonymously under the name “Pony Alpha.” That possibility fit a wider backdrop in which Chinese labs, including DeepSeek and Moonshot, have been pressing US competitors with capable, lower-cost, often open models.

But the identification case quickly frayed. A competing analysis raised the possibility that Ox Alpha’s tokenizer instead resembles Microsoft’s MAI family, potentially making the model an unreleased Microsoft system rather than a Chinese entrant. On Saturday, analyst Andrew Curran captured the reversal: GLM had been the leading theory the prior night, but “people seem less sure of anything.”²

The dispute has spread beyond analysts. Reddit users have argued both that Ox Alpha “can’t be the Chinese” and that it is Chinese with “high confidence,” while OpenRouter’s own listing offers no name to settle the argument: the preview was “developed and operated by a third-party provider” that chose to remain anonymous.²

For now, the consensus is limited to the model’s impact. Ox Alpha has impressed early users; its provenance remains a far more contested benchmark.