Stealth line · Union Alpha · pricing
Is Union Alpha free?
Short answer: it was, for two days, and it is not any more. Here is what “free” meant on the anonymous endpoint, exactly when it ended, what the revealed model costs instead, and how to check any of it yourself in ten seconds.
The whole window, in one table
| Field | Value | Status |
|---|---|---|
| Model id | stealth/union-alpha | Delisted 2026-09-18 |
| Price during the window | $0 / $0 | Verified 2026-09-16 → 09-18 |
| Revealed as | unbiased/pareto | Verified 2026-09-18 |
| Price now, per million in / out | $2.50 / $7.50 | Verified 2026-09-18 |
| The price that was reported during the window | ≈ $0.50 in / $1.50 out per million | Claim — did not hold |
| Notice before it changed | None published | It changed without one |
openrouter.ai/api/v1/models Verified 2026-09-18 Live re-check: /api/union-alpha/status What “free” means on a stealth endpoint
A stealth preview is a lab testing an unreleased model in public. The free price is the incentive to get people to use it: you supply the traffic and the feedback, the lab supplies the compute. That arrangement ends when the test does.
It also means the endpoint has no commercial obligations to you — no SLA, no published data-retention terms, no support channel and no notice period. Everything on this page is written with that in mind.
What happened to the Alpha models before this one
All three revealed codenames have ended the same way, which is the closest thing to a forecast that exists — a precedent rather than a rule, as it was when this page first said “the last two”. A fourth broke it: Space Bunny Alpha was free and unclaimed for its whole run, 23 September to 5 October 2026, and delisted without a maker ever naming itself.
| Codename | Revealed as | What happened to the free window |
|---|---|---|
| Hunter Alpha | Xiaomi MiMo-V2.5 | Repriced as a normal paid model after the reveal |
| OX Alpha | Z.ai GLM 5.3 Flash | Folded into the vendor's own lineup at its list price |
| Union Alpha | Unbiased Pareto | Revealed and delisted on day three; relisted under its real name at list price |
Deeper background: how the Alpha line works.
Checking any of this yourself
- Ask our status endpoint. /api/union-alpha/status
reads the catalogue live and returns whether
stealth/union-alphais still listed, with its price and context window when it is. It currently answers “no longer listed”. - Or read the listings. The stealth page at openrouter.ai/stealth/union-alpha ↗ still carries the reveal notice, and the live per-million price for the revealed model is on openrouter.ai/unbiased/pareto ↗ .
- Watch the price against the identity. On this line the free tier has ended with the reveal every time, so the reveal is the event to watch, not the price history.
If you built on it
-
Swap
stealth/union-alphaforunbiased/pareto— same model, same 262,144-token context window, now billed. - Keep a fallback model configured and tested, so the next delisting is a config change rather than an outage.
- Log which model served each request — an anonymous endpoint that disappears is hard to reason about after the fact.
- Re-check your cost estimate against the real listing: $2.50 in / $7.50 out per million, not the ≈$0.50 / $1.50 that was circulating while the model was anonymous.
- Keep secrets and other people's data out of preview endpoints. The anonymous window is closed now, but the next codename will behave the same way.
FAQ
Is Union Alpha free right now?
No. It was free for the two days of the stealth window, 2026-09-16 to 2026-09-18, and is not any more: stealth/union-alpha was removed from the OpenRouter catalogue when the model was revealed as Unbiased Pareto, which is listed at $2.50 per million input tokens and $7.50 per million output tokens.
How long was it free?
Two days. Listed 2026-09-16, revealed and delisted 2026-09-18. That is the third time in a row for this line: every Alpha codename so far has been free while anonymous and repriced or folded into the vendor's own lineup once the identity came out.
What does it cost now?
The family bills at $2.50 per million input tokens and $7.50 per million output tokens, read from the public catalogue on 2026-09-18 under the id unbiased/pareto and again on 2026-10-16 under its dated replacement, unbiased/pareto-26.9. The ≈$0.50 / $1.50 figure that circulated during the anonymous window was a third-party claim about an unreleased model, and the real listing did not match it — which is the argument for pricing off the catalogue and not off the rumour.
Was anyone told before the free window closed?
No. Nothing was published in advance by the maker or by OpenRouter; the delisting and the reveal arrived together. Free stealth previews on this line have now ended without notice three times, so the honest planning assumption is that a free endpoint is unannounced on the way in and unannounced on the way out.
Get told when the next codename appears
One email when the next stealth model is listed — and one when its identity comes out.
Union Alpha tracker → Using it in OpenCode Errors and limits