Union Alpha: The Reference Page for the Stealth Model Listed as union-alpha-free

Union Alpha is a stealth-preview model — an anonymous provider's model, published under a code name with no lab attached to it — carried in OrcaRouter's catalogue from 17 September 2026 under the identifier stealth/union-alpha-free and no longer resolving there as of 28 September 2026, with a 262,144-token context window, a 131,072-token output ceiling, text and image input, text output, and a listed price of zero dollars per million tokens on both sides. This page is the reference for it: the destination for someone who searched the model's own name, not a second announcement that it exists.

Two things about how to read what follows, starting with why the page exists. This is not a news article about a dated event. It is the canonical reference page for a model whose name people search for directly — the page a reader reaches after typing the model's own name. Its warrant is standing search demand we measured first-party on 28 September 2026, not the freshness of a launch: 17,117 impressions and 503 clicks across the union-alpha query family in the 28 days to 25 September, with the head term "union alpha" alone at 16,453 impressions and 464 clicks at position 7.4, "union alpha free" at 1,915 impressions and 50 clicks, "union alpha model" at 1,377 and 25, and "union alpha benchmark" at 571 impressions and 26 clicks. The datable anchor — the 17 September 2026 listing — is used here as a fact that dates the model, not as an event to report.

The other note is provenance, and it matters more than usual for this model. Every figure below is labelled with where it came from. The envelope, the rate card and the endpoint surface are platform listing metadata: the operator's own numbers, published on the model's listing page and read there on 17 September 2026, the last date on which that page resolved. None of it is independently verified, and for a provider who declines to be named there is no second party to verify it against. Where this page re-checked something on 28 September 2026 and got a different answer, it says so in the section where it belongs rather than quietly substituting the newer reading.

The model as documented

Union Alpha is a vision-capable multimodal text model in the pattern this family of anonymous listings follows: a code name, a free price point, a large context window, and an operator who stays unnamed while the model is evaluated. The listing's own tagline positions it as frontier-level performance from an anonymous lab — a marketing line, not a measurement, and worth reading as such. What the listing does state as fact is a spec sheet, and the spec sheet is unusually specific for a cloaked model: a quarter-million-token context, a very large output ceiling, image input, tool calling and JSON output, all at no cost.

What it does not state is anything about identity. There is no lab name, no parameter count, no architecture, no licence, no weight release, and no knowledge cutoff — the tokenizer field is filled only as "Other", which is a placeholder rather than an answer. The listing's operator block reads "stealth" and carries the notice that the entry is cloaked while the model is being evaluated and that capabilities and availability may change without notice. That notice is the single most load-bearing sentence on the page, and it is the reason to treat everything here as a snapshot with a date on it.

The free tier, and what the card actually said about limits

This is the loose query with the most volume behind it, so it deserves a direct answer rather than a paragraph of hedging. The listing priced Union Alpha at $0.00 per million input tokens and $0.00 per million output tokens, and it described the free access as rate-limited: a request that crossed the cap returned HTTP 429 rather than a charge. Both of those facts were read on the model's own listing card on 17 September 2026.

They could not be re-read on 28 September 2026, and that is the honest answer to the question today. The listing page no longer resolves — see the availability section below — so there is no live card to re-read the $0 rate or the 429 behaviour from. What can be said without reaching past the evidence is this: a $0 list price and an HTTP 429 rate limit are what the card said on the date it existed, and no rate-limit figure — no requests per minute, no requests per day, no token quota — was ever published on it. If you need the current terms, they are not on this page and they are not on the listing either, because there is no listing to read them from.

One piece of context that is a property of the platform rather than of this model, and is worth stating because it bounds what a free tier here can mean: OrcaRouter's published free-package tiers are 10 requests per minute and 50 per day at the entry level, rising to 20 per minute and 800 per day once an account has $20 of paid usage. Those are the platform's tier figures, read from the free-package endpoint on 28 September 2026, and they are not a statement about Union Alpha's own limits, which were never published.

Context window and output ceiling

• Context window — 262,144 tokens. Listing metadata, read 17 September 2026. The listing's footer states it in shorthand as 262K context.

• Maximum output — 131,072 tokens. Same source and date. Half the context window, which is a generous ceiling and one nobody has publicly stress-tested for coherence at the far end.

The pair is worth reading together, because the ratio is the unusual part: most listings in this class cap output far below half the context window. It means a single call can return a document the size of a small book, and it also means a runaway generation has a long way to run before max_tokens stops it.

Input and output modalities

• Input — text and image. Listing metadata, read 17 September 2026.

• Output — text only. Same source and date. No image generation, no audio, no video.

This is a vision-in, text-out model and nothing wider. Image input arrives through the same chat call as text rather than through a separate endpoint, which is convenient and also means an image competes for the same context budget as the rest of the conversation. The card's "can provide" line reinforces the same picture: vision, tools and JSON, with no audio or video anywhere on it.

Declared capabilities

• Vision — declared, via the image input modality above.

• Tools — declared. The listing accepted the tools and tool_choice parameters, so function calling is available.

• JSON output — declared, via response_format. The card does not claim JSON-schema enforcement, so treat structured output as JSON-shaped rather than validated. If your pipeline needs a guaranteed object back, validate it yourself.

• Reasoning — the card's reasoning field is empty. Unlike the other anonymous previews in this series, no reasoning parameter and no effort ladder are published for Union Alpha. That is a blank on the card, not a statement that the model does or does not reason.

All four lines come from the same listing read on 17 September 2026.

The endpoint surface

What a caller actually got, taken from the listing's accepted-parameter set rather than from prose documentation. Same source and date as everything above.

• Sampling and limits — max_tokens, temperature, top_p.

• Structure — response_format, for JSON output without schema enforcement.

• Tools — tools and tool_choice, so function calling is available and the model can be told to choose its own tool.

That is the whole surface: six accepted parameters, one chat-shaped call. No separate vision endpoint, no batching API, no embeddings, no fine-tuning path, and no reasoning controls, because the card publishes none. The parameter set is the same shape the platform uses across its catalogue, which is the one convenience of an unfamiliar model on a familiar API — nothing about the call changes when the model behind it is anonymous.

What the listing did not document

Stated plainly, because a gap in the record is itself a fact about this model, and one that a stealth listing makes easy to paper over with inference.

• Benchmarks — none. The listing carried a public benchmarks panel and it read pending, with no table, no scores and no runs beneath it. The catalogue entry's own quality score was zero. There is therefore no quality baseline for Union Alpha from any source, and no honest way to rank it against any model. A page that puts it on a leaderboard is inventing the placement.

• Independent measurement — none found. The independent leaderboards we would normally cite for cross-model comparison carry no entry under this name, and no third party has published a run of any kind. Nothing has been replicated by anyone.

• Provider — undisclosed, and the listing said so itself: the entry is operated by a provider identified only as stealth, cloaked while the model is evaluated. There is no lab name, no status page and no escalation route. We are not going to guess at which lab that is, and neither should anyone else reading this. A matching benchmark score or a similar token count is a resemblance, not an identification, and a community guess presented as a finding is worse for a reader than an honest blank.

• Throughput and latency — thin, and mixed. The card published a tokens-per-second figure of 225 tok/s and an error rate of 1.1% across 1.2M tokens served over the seven days to 17 September, both of them platform-published listing telemetry. It also published a performance panel showing a p50 and p95 time to first token of 10.00 seconds each, over the window 16 to 23 September 2026 — a pair that reads as a single measurement bucket rather than a distribution, because both percentiles landed on the same figure. Treat the latency number as one sample, not a curve. Both sets of figures are platform telemetry from the listing, not an independent test.

Availability on OrcaRouter, checked today

This section is here because the answer changed, and because the earlier coverage of this model described a served endpoint that no longer resolves.

On 28 September 2026 the identifier stealth/union-alpha-free is not in our live catalogue. Checked directly and independently of one another: the model's public API record returns HTTP 404 for that identifier while returning a full record for models that exist, so the 404 is a real absence rather than a broken probe; the catalogue's full pricing list, 200 entries including delisted and upcoming models, contains no entry matching that name or any stealth vendor; the platform's free-package list, the authoritative list of free aliases, names four models and Union Alpha is not among them; and the rendered catalogue reports its current model and provider counts with no stealth vendor present. The model page itself returns "Model not found".

Two consequences follow, and they are worth separating. The first is that the envelope above is a reading of a listing that existed on 17 September 2026 and is not a description of a callable endpoint today. The figures are not wrong; they are dated, and the date is the whole reason they are labelled. The second is narrower and more practical: this page is not a route to Union Alpha. We cannot offer it, we cannot route to it, and nothing here should be read as an availability claim, because the check that would support one failed. The sibling coverage of this model's listing, which described it as served on the free tier, was accurate to the endpoint as it existed on 17 September 2026 and should be read with that date attached to it; today's check does not reproduce it.

What we can speak to is the platform around it. OrcaRouter runs 200+ models behind a single API at provider list price with no markup, so a vendor's own price change is live on our side the same day, with automatic failover across providers for the traffic you do route through us. That is a statement about the catalogue, not about Union Alpha, which is not in it.

What would change this page

• A named owner. Every anonymous preview in this series so far has eventually been claimed by a named lab, and a name arrives with a parameter count, a licence and usually a price. That would move Union Alpha out of the stealth class entirely and make most of this page obsolete.

• Any benchmark at all. One published run, from any source willing to say how it was produced, would give the model the quality baseline it currently lacks. Until then the honest position is that its capability is unmeasured.

• A live listing again. If the endpoint returns, the $0 rate and the 429 behaviour need re-reading from the card before anyone repeats them as current.

• Published rate limits. The largest unanswered question about this model is not how good it is but how much of it you can have, and the card never answered it.

Until one of those lands, the honest summary is short. Union Alpha is a 262,144-token, image-capable, tool-calling text model with an undisclosed operator, a zero-dollar list price and a 429 at the cap, all of it read from a listing on 17 September 2026 that no longer resolves on 28 September 2026. No benchmark exists, so it cannot be ranked; no provider is named, so it cannot be chased; and as of today's check it is not a model we can route to. Everything else about it is a date-stamped snapshot, and this page is the place to check which snapshot is current.