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WinnerDeck

Fairness & verification

Fair by design, checkable by anyone

Here is exactly how official draws pick winners — and what our verification does and does not prove.

1

Winners are selected on the server, never in your browser

When you press Draw, the countdown and shuffle start immediately over neutral placeholder names while our server picks the winners and saves them. No real name is ever revealed until the winners are saved — the countdown, shuffle and confetti are presentation only. They can't change the result, and neither can refreshing the page or clicking twice.

2

The candidate list is snapshotted and hashed

Eligible participants are put in a deterministic order, and the full ordered list is stored with the draw alongside its SHA-256 fingerprint. The receipt shows this candidate hash, so the list the draw ran on can't be quietly swapped afterwards.

3

Randomness comes from a stored cryptographic seed

Each draw generates a secure 32-byte random seed. That seed drives a deterministic HMAC-SHA256 random stream, which feeds a Fisher–Yates shuffle with rejection sampling — the textbook way to sample winners without bias. The algorithm is versioned (hmac-sha256-fy-v1) and named on every receipt.

4

Every official draw can be replayed

Because the seed, the ordered candidate snapshot and the algorithm version are all stored, the draw can be re-run at any time. The verification page replays the exact computation on the server and compares the reproduced winners with the saved ones.

Honest limits: what replay verification proves

We would rather under-promise than overclaim. Replay verification is strong evidence, not magic.

Verification proves

  • The stored result is internally consistent: the saved seed, candidate snapshot and algorithm reproduce exactly the saved winners.
  • The candidate list the draw used has not been altered since the draw — its hash still matches.
  • The selection used an unbiased, versioned algorithm, not a manual pick.

Verification does not prove

  • That the candidate list itself was complete or correct before the draw — verification cannot tell you whether the organizer omitted or added entrants.
  • Who was behind each entry, or whether entries met the organizer's own eligibility rules.
  • Anything about draws run outside the platform.

In short: verification proves the published result really came from the stored candidate list, seed and algorithm — it cannot audit the world outside the draw. Organizers who need entrant-level transparency should share their participant criteria alongside the receipt.

What about the Quick Picker?

The free Quick Picker runs entirely in your browser: names never leave your device, so there is no server record and no receipt. Selection still uses your browser's cryptographic randomness (Web Crypto's getRandomValues with unbiased rejection sampling) — never Math.random(). If you need a draw others can verify later, run it as an official draw in a saved event.

Try the Quick Picker

Pick winners beautifully.

Create your first event free. Prove every draw was fair.

Create free eventTry Quick Picker