Hunter Alpha → Xiaomi MiMo-V2.5
11 daysFree preview ended with the reveal; the model reappeared as a Xiaomi product with published pricing and a 1.05M-token window.
Stealth line · register
Stealth models on OpenRouter
Anonymous releases we can point at a public listing — nothing rumoured, nothing unverifiable. 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 have followed that script on OpenRouter since March 2026; a fourth, Space Bunny Alpha, followed all of it except the last part — it ran for thirteen days, led the platform by token usage, and delisted on 5 October 2026 without anyone claiming it.
This page is the index. The narrative version — the staging pattern, and how to judge the next drop — is on the Alpha models line.
Index of documented stealth releases
The arithmetic over these rows — how long each codename stayed anonymous, how often they arrive, and what the reveal did to the price — is The Alpha Line Report, with a JSON twin and a licence that says quote it.
| Codename | First listed | Turned out to be | Status |
|---|---|---|---|
| Space Bunny Alpha | 2026-09-23 | Not revealed | Ran 23 Sep → 5 Oct 2026, led the platform by token usage, left unclaimed. Read 2026-10-06 |
| 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 | Unbiased Pareto | Yes — revealed 2026-09-18, stealth route delisted |
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.
The line, side by side
This is the table we extend every time a codename appears. While a model is anonymous the fields come from a catalogue read; after the reveal they come from the product page it became. The two sources are labelled, because they are not the same kind of fact.
| Codename | First listed | Context | Input | While anonymous | Revealed as | Price after |
|---|---|---|---|---|---|---|
| Space Bunny Alpha | 2026-09-23 | 1M | Text + image + video in | Free | Not revealed — lead: MiniMax | — |
| Hunter Alpha | 2026-03-12 | 1M | Text only | Free | Xiaomi MiMo-V2.5 | $0.14 in / $0.28 out per M |
| OX Alpha | 2026-08-20 | 1M | Text only | Free | Z.ai GLM 5.3 Flash | $0.15 in / $0.50 out per M |
| Union Alpha | 2026-09-16 | 256K | Text + image in | Free | Unbiased Pareto | $2.50 in / $7.50 out per M |
Source
OpenRouter catalogue reads + each model's own product page Verified 2026-09-17 Union Alpha's post-reveal price is a third-party published figure, not an announcement The one number here that neither we nor a vendor has confirmed is Union Alpha's post-reveal price. Details: is Union Alpha still free?
What the reveal did to the price
OX Alpha → Z.ai GLM 5.3 Flash
WeeksZ.ai claimed it as GLM 5.3 Flash and folded it into the vendor line at list price, with the largest window on this site at 1.31M tokens.
How to judge the next drop
- 1 Confirm it is in the catalogue
A codename has to resolve to a real listing before it means anything. Ours is a live read, not a screenshot: /api/union-alpha/status is the shape to copy.
- 2 Check what the endpoint declares
Context window, output cap, modalities and tool support come from the catalogue and can be re-read in seconds. Everything else is commentary.
- 3 Read the price as a countdown
While it is free, the model is in a trial. The day the price stops being $0 is the day the reveal is either done or imminent.
- 4 Separate the community's claims from the listing
Identity theories are worth reading and worthless as evidence. Keep them in a separate column or a separate section — never blended into a spec table.
- 5 Decide before the window closes, not after
If you evaluate a stealth endpoint, evaluate it in days and keep a fallback configured. The two reveals we documented both ended the free window with no notice.
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 ones listed here?
Four are in the table today — three revealed, one delisted without ever being named. 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.
How many stealth models has OpenRouter had?
We can document four: Hunter Alpha (March 2026), OX Alpha (August 2026), Union Alpha (September 2026) and Space Bunny Alpha (23 September – 5 October 2026, delisted and still unnamed). The list is short on purpose — a codename that cannot be tied to a public listing is not included, and folk names circulating in forums are exactly the kind of thing this index refuses to guess at.
What is the difference between /stealth-models and /alpha-models?
This page is the index: every documented release, with the fields you can re-check. /alpha-models is the explainer: why the releases are staged this way, what the codenames have in common, and what tends to happen at the reveal. Same subject, different question.
Union Alpha → Unbiased Pareto The Alpha line explained Free models today Compare every model