Provably fair

How every flip on FLIP can be independently verified.

Every coinflip result on FLIP is generated with a commit-reveal scheme, which means the server locks in its randomness before anyone joins the flip — and proves it afterward.

How it works

1. When a flip is created, the server generates a secret random seed and immediately publishes its SHA-256 hash — the commit. You can see this commit on every open lobby.
2. When a second player joins, the server generates a random salt, then computes SHA-256(seed + salt). If the first byte of that digest is even, the coin lands heads; odd lands tails.
3. After the flip resolves, the seed, salt, and original commit are all revealed in the result screen.

Verify it yourself

Take the revealed seed and confirm that SHA-256(seed) equals the commit you saw before the flip. Then compute SHA-256(seed + salt) and check the first byte's parity against the published result. If the commit matches, the server could not have changed the seed after seeing who joined or which side they were on.

Any hash tool works — for example echo -n "seedsalt" | sha256sum in a terminal, or any online SHA-256 calculator.