Coinflip

1. 1
   Round opens with a sealed commitment. Before any deposit, the server generates a secret random salt and publishes SHA-256(salt). The salt itself stays hidden, so it is locked in before anyone deposits.
2. 2
   Players deposit and the pot fills. Each $0.01 deposited is one ticket, so your share of the pot is your share of the odds. A bigger deposit means a wider slice of the range and a higher chance.
3. 3
   Round closes and a second seed comes from drand. When the pot locks, we draw a public random value from the drand beacon (the League of Entropy), which nobody, us included, can predict or control. The server seed and the drand value are joined as serverSeed-drandRandomness, hashed with SHA-256, and the first 13 hex digits become the winning ticket in [0, 1): int(SHA-256(serverSeed-drandRandomness)[0:13], 16) / 16^13. The winner is whoever's cumulative range holds it. The drand round is chosen to land after the pot locks, so its value is unknown to everyone at that moment. Anyone can recompute SHA-256(serverSeed) to confirm the committed hash, then re-run the formula to confirm the ticket.
4. ✓
   Open the "Verify a round" tab to paste the values from any past round and confirm the math yourself. It runs in your browser and pulls only the public drand value, from a beacon nobody controls, so you never have to trust us.

These fill in automatically: open a finished round from Recent Rounds and click Verify in Provably Fair. A round's seeds and ticket are only revealed after it ends, so a round still in progress can't be verified yet. You can also paste the values from any past round by hand.