DonutBeam

Verify, do not trust

Provably fair

No result on DonutBeam is decided after your bet. Here is how to prove that yourself.

  1. Step 1

    Before your bet

    The server draws a secret seed and publishes only its SHA-256 hash. It is committed to an outcome it can no longer change.

  2. Step 2

    Your half

    You set your own client seed and can change it whenever you like. It feeds the calculation, so the server cannot know the result in advance.

  3. Step 3

    The draw

    The result is HMAC-SHA256(server seed, client seed : nonce). The nonce goes up by one each round, so no two rounds land the same way.

  4. Step 4

    The reveal

    When you rotate your seed, the old server seed is published. Hash it, check it matches what was posted, then recompute every round you played on it.

Check a round

Paste the seeds from a finished round. The maths runs on your machine, using the same code the games use. Nothing is sent back to us.

What about the live tables?

Crash, Roulette and the other shared tables draw from a hash chain. The terminal hash is published before the chain opens, each round is the hash of the one after it, and the whole chain is salted by the public drand beacon. Since nobody can reverse SHA-256, the sequence is fixed before the first bet and checkable round by round afterwards.

Fair is not the same as even

Provably fair means the draw is honest. It does not mean the game is even. Every game keeps a house edge — 1% on most originals — and that edge is the only cut the site takes. Over enough rounds the house wins. Play with what you are happy to lose.