Verify a FairSpin Draw

Paste a draw's seed and entry list below and this page re-runs the exact draw math in your browser — showing every step. If the recomputed winner matches the announced winner, the draw was fixed before anyone saw the result.

How to prove a giveaway draw was fair

Running an online giveaway? "Trust me, it was random" convinces nobody — and screenshots of a wheel mid-spin prove even less, because most wheels decide the winner during the animation. Here's the process that actually holds up when a winner (or a losing entrant) asks questions:

1. Publish the inputs before announcing. In FairSpin, every draw produces a random seed and a SHA-256 fingerprint of the exact entry list. Post both publicly — in the video description, the giveaway thread, or the classroom channel — before you reveal who won. This commits you to the inputs; you can't quietly swap the entry list afterward because the fingerprint would change.
2. Let anyone re-run the draw. Send skeptics to this page. The seed, the entry list, and the draw number deterministically reproduce the winner through the steps shown above — the same cryptographic hash function, the same weighted slice math. No trust required: the math is checkable by anyone, including with independent SHA-256 tools.
3. Keep the entry list honest. Verification proves the published inputs produce the announced winner. It does not prove you only spun once — a dishonest host could spin repeatedly and publish the most convenient result. The defense is procedure: draw live on camera, publish the seed immediately, and never re-draw without announcing it. For high-stakes draws, have a neutral third party supply part of the seed.
4. Mind the names. Entry lists for classroom draws often contain students' names. FairSpin never uploads them — verification happens entirely in the visitor's browser — but think before publishing a full roster publicly. Initials or seat numbers work fine as entries.

What verification proves — and what it doesn't

It proves: the winner shown is the deterministic output of the published seed, entry list (names, weights, order), and draw number — computed with SHA-256 and standard weighted-random math. Alter any input and the output changes, so a matching result means the inputs are exactly what was drawn from.

It doesn't prove: that the draw was the only draw (see step 3 above), that the entry list itself was assembled fairly, or that the device's random number generator wasn't compromised — the last of these is a theoretical concern on stock browsers and operating systems, whose cryptographic RNGs are considered excellent. For legally binding lotteries or gambling, use a licensed system; FairSpin is a decision helper, not a gambling device.

Technical details of the draw derivation are documented in How Fairness Works.