OpenCode's model catalog recently gained an unusual entry: Union Alpha Free — a model with no named vendor, a $0 price on every meter, and a 262,144-token context window. Stealth launches like this are how providers road-test a model under real workloads before attaching a brand to it. This guide shows how to try it in OpenCode, what we verified ourselves, and the caveats worth reading before you point it at real work. Disclosure: Wallaby Token sells API access to kimi-k3, a different model in the same catalog — we have no affiliation with whoever is behind Union Alpha, and we wrote this because "what is Union Alpha?" is a question our own team asked this week.
What Union Alpha Free actually is
Only what can be observed:
- It appears in OpenCode's synced catalog as
opencode/union-alpha, served through OpenCode's own zen endpoint. - Every price field reads $0 — input, output, cache. It costs nothing to call today.
- Advertised limits: 262,144 tokens of context, 131,072 max output — generous by any standard.
- No provider name, no model card, no weights. "Stealth" means the operator is choosing not to say whose model this is.
Anything beyond that — whose weights they are, whether it stays free, what the data policy really is — is speculation or someone else's claim, and we will not dress speculation up as fact here.
How to use it
If you already have OpenCode, this is under a minute:
opencode models --refresh # pull the latest catalog
opencode models | grep union
# opencode/union-alpha
Then either select Union Alpha Free via /models in the TUI, or one-shot it:
opencode run -m opencode/union-alpha "Explain what a bloom filter is in two sentences"
No API key, no account, no billing page — the calls route through OpenCode's zen endpoint, not your own provider credentials.
Our verification run (September 17, 2026), unedited:
$ opencode run -m opencode/union-alpha "Reply with exactly three words: Union Alpha works"
Union Alpha works
New to OpenCode entirely? Install is one line — curl -fsSL https://opencode.ai/install | bash — with one zsh PATH gotcha worth knowing; our OpenCode setup guide covers it step by step.
Read this before real work
Three honest caveats, in order of importance:
- Do not paste anything you would not hand a stranger. Stealth means you do not know who operates the endpoint, and any data-handling promises are the provider's own claims, not audited facts. For evaluation prompts and throwaway code, fine. For client work, credentials, or unpublished IP, no.
- Free is a launch posture, not a contract. Zero pricing on a 262k-context model is a user-acquisition play. Stealth models typically get claimed, rebranded, rate-limited, or priced once the test phase ends. Enjoy it, but do not build a workflow that depends on it staying free — or staying.
- There is no SLA, no status page, no bill. That is fine for a free experiment. It is not fine as production infrastructure.
When you outgrow it
The natural graduation path is a named model with a published price, an itemized bill, and someone accountable on the other end — without leaving the tool you just learned. Kimi K3 is in the same OpenCode catalog (wallaby/moonshotai/kimi-k3): one environment variable, a hard-capped prepaid balance so spend can never surprise you, per-token itemized logs, and a public status page. New accounts get $0.50 in trial credit, and our setup guide takes about two minutes. Same TUI, same /models picker — you just know whose model you are running.
The bottom line
Union Alpha Free is worth an afternoon of your curiosity: 262k context at $0 is a genuinely useful sandbox while it lasts. Treat it as exactly that — a sandbox — and keep your real workloads on models with names, bills, and accountable operators.