Stealth models on OpenRouter
Anonymous releases we can point at a public listing — nothing rumoured, nothing unverifiable. Last verified 2026-09-17. Live entry: Union Alpha.
A stealth model is a frontier-class model published anonymously as a free preview, then claimed and renamed once the maker is ready to talk about it. Three of them have followed that script on OpenRouter since March 2026. This page is the index; the narrative version, with the staging pattern and how to judge the next drop, is on the Alpha models line.
Index of documented stealth releases
| Codename | First listed | Turned out to be | Status |
|---|---|---|---|
| Hunter Alpha | 2026-03-12 | Xiaomi MiMo-V2.5 | Yes — maker disclosed, model renamed and repriced |
| OX Alpha | 2026-08-20 | Z.ai GLM 5.3 Flash | Yes — maker disclosed, model renamed and repriced |
| Union Alpha | 2026-09-16 | Unclaimed | No — live now, maker anonymous |
Why the list is short: when a stealth model is revealed, the codename normally vanishes from the catalogue. Anything we cannot tie to a listing is left out rather than guessed at.
How a stealth release is staged
- Anonymous listing. The model appears in a public catalogue under a neutral namespace, free, with a context window above its price class.
- Silent measurement. The maker collects real usage and preference signal under a name that carries no brand expectations.
- Reveal and rename. If it performs, the maker claims it, the codename is retired and pricing starts.
FAQ
What is a stealth model?
A model published to a public catalogue — most often OpenRouter — with no announcement, no maker name and usually no price while it is in preview. The codename is temporary: if the release goes well the maker claims it and renames it to a product name.
How long does a stealth model stay anonymous?
In the cases we can verify, weeks rather than months. Hunter Alpha was revealed as Xiaomi MiMo-V2.5 and OX Alpha as Z.ai GLM 5.3 Flash; both kept their free window only until the reveal, then were repriced. Treat the anonymous phase as a trial period, not a stable endpoint.
Are there other stealth codenames besides the three listed here?
Codenames appear in forums that we cannot verify against a public listing — and once a model is revealed, the old codename usually disappears from the catalogue entirely, which is why this index only lists releases we can document. If a codename is not in the table, we have no evidence for it.
Is it safe to build on a stealth model?
No. There is no named provider, usually no published privacy or data-retention policy, and the endpoint can be repriced or withdrawn without notice. Use stealth endpoints for evaluation with non-sensitive data, and keep production on models with a disclosed vendor.