“Provably fair” is a system that lets you check that a game result wasn't changed after you placed your bet. It's common in crypto casinos' own games, like dice, crash and plinko.
How it works
Each result is calculated from three ingredients:
- Server seed: a secret value from the casino. Before you play, the casino shows you a hash of it, a fingerprint that can't be reversed but proves the seed won't change.
- Client seed: a value from you, or your browser, which you can usually change.
- Nonce: a counter that goes up by one with every bet.
The game combines the three to produce the result. Later, when you change seeds, the casino reveals the old server seed. You can then check that it matches the hash you were shown, and recalculate every past result yourself.
How to check a bet
- Open the casino's fairness or provably fair page.
- Rotate your seed pair to reveal the previous server seed.
- Confirm the revealed server seed matches the hash shown before you played.
- Use the casino's verifier, or an independent one, to recalculate a result from the server seed, client seed and nonce.
What it proves, and what it doesn't
Provably fair proves the casino didn't change a result after your bet. It doesn't prove:
- that the house edge is low; that's set by the game rules and payout table;
- that the casino will pay your withdrawal;
- anything about third-party slots, which use their own certified random number generators instead.
So it's a useful honesty check for in-house games, not a safety rating for the whole casino. For that, look at payout reports, ID-check thresholds, licence details and complaints. On WhatOBet each fact shows its source.
Remember
Every game still has a house edge, so over time the casino is expected to win. Treat any game as paid entertainment, and set a limit before you start.