What "provably fair" actually means for a giveaway
Run a giveaway with more than about forty people watching and somebody, eventually, will type "rigged" in chat. Doesn't matter if you used a fair wheel, a fair raffle app, or pulled a name out of an actual hat on camera. Enough viewers have been burned by a sketchy giveaway once that the accusation is basically background radiation now. "Provably fair" is the answer that doesn't ask them to just trust you.
It's a phrase crypto casinos popularized, and it sounds more complicated than it is. The whole trick fits in one sentence: publish proof of a decision before you reveal what the decision was. Here's the version we built into the wheel.
The three moves
When you flip on provably-fair mode and hit spin, three things happen in order, and the order is the entire point.
First, the wheel generates a random seed — just a string of random bytes, something like a91f..., picked with crypto.getRandomValues. Nobody sees this yet, not even you, really; it's generated and immediately run through SHA-256, a hashing function that turns any input into a fixed-length fingerprint. Change one character of the seed and the fingerprint comes out completely different. That fingerprint is what gets shown on screen, before the wheel even finishes its first rotation.
Second, the wheel spins. Your entry list is locked the moment the hash appears — you genuinely cannot edit it until the spin lands, which matters more than it sounds like it should.
Third, once the wheel stops, the actual seed is revealed. Type that seed into our Verify panel, or into any SHA-256 tool you trust more than us, and hash it yourself. If your fingerprint matches the one published before the spin, the seed wasn't swapped out after the fact. And since the winner is calculated straight from the seed — not chosen separately — a matching hash means the winner wasn't swapped either.
Why the one-way part matters
A hash function only works for this if it's a one-way street. Given the seed, computing the hash takes microseconds. Given only the hash, working backwards to find a seed that produces it is, for practical purposes, impossible — there's no shortcut, you'd be brute-forcing your way through more possibilities than there are atoms worth counting. That asymmetry is the whole mechanism. It's why the hash can be shown safely before anyone knows the seed, and why revealing the seed afterward is what unlocks the check, not something that could have unlocked it earlier.
What it doesn't cover
Being straight about the gaps matters more than the sales pitch, so: this scheme proves the seed wasn't changed between commit and reveal. It does not prove your entry list was honest to begin with. A host could still quietly load the wheel with five extra entries for their friend before ever hitting spin, and the hash alone won't catch that — which is exactly why we lock the entry box the instant the hash appears, and why the Verify panel asks for the entry list too, not just the seed. Screenshot that list before you spin. Read chat the names out loud. The math handles the part that math can handle; the rest is still on the host to show their work.
One more honest caveat: none of this is audited by a third party, and it's not a licensed gaming product. It's the same commit-reveal idea a lot of trustworthy giveaway tools use, built with the same web-standard SHA-256 every browser already ships. Good enough for a Twitch raffle. Not a substitute for a licensed sweepstakes if actual money is on the line and lawyers are involved.
Checking someone else's spin
You don't need our site open to verify a result somebody else posted. Take the seed, take their entry list in the order they had it, run it through SHA-256, and take the first 32 bits of the output as a number between zero and one. Multiply that by the total weight of the list, walk down the entries adding up weights until you pass that number, and whichever entry you land on is the winner. That's the entire algorithm — no secret sauce, nothing that needs our server, because there is no server. Our Verify panel just does that arithmetic for you instead of by hand.
Rigged-wheel accusations aren't going away. What changes is whether you can answer them with math instead of a promise.