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Provably Fair, explained and verifiable
Provably fair lets you mathematically check that a game round was fixed before you bet and never altered afterwards. Here is exactly how it works — and how to test it yourself.
What "provably fair" means
Provably fair is a cryptographic system used by crash games and many crypto-casino originals (Aviator, Chicken Road, dice, plinko and more) that lets you verify a result was not manipulated. Instead of trusting the operator, you can reproduce the outcome from public inputs after the round. It proves honesty — it does not remove the built-in house edge, which is a separate thing our calculators show.
The three ingredients
- Server seed — a secret string the casino generates. You see only its hash before the round; the full value is revealed afterwards so you can check it.
- Client seed — a string from your browser (you can usually change it), which guarantees the casino could not pick a result knowing your seed in advance.
- Nonce — a counter that increases each round, so every bet with the same seeds produces a different, fixed outcome.
How a round is generated
The casino combines server_seed : client_seed : nonce and runs it through a hash function such as SHA-256. A slice of that hash is turned into a number, which maps to the game result — for a crash game, the multiplier where the plane flies away; for Chicken Road, the lane where the run crashes. Because the server seed was committed (hashed) before the round, the result was locked in before you bet.
Our
Aviator and
Chicken Road calculators include a live
fairness verifier tab: enter seeds and a nonce and the same inputs always produce the same outcome, changing the nonce moves it somewhere you could not have known. That is provably fair in action.
How to verify a round yourself
- Before playing, note the hashed server seed the casino shows and set (or note) your client seed.
- Play the round and record the result and the nonce.
- After you rotate seeds, the casino reveals the unhashed server seed. Hash it and confirm it matches the commitment you saved.
- Recompute
SHA-256(server_seed:client_seed:nonce) and map it with the game's public formula — it must equal the result you saw.
If every step matches, the outcome was fixed in advance and untouched. If the revealed server seed does not hash to the earlier commitment, the game is not honest — walk away.
What provably fair does not do
It does not make a game beatable. Every provably-fair game still keeps a house edge (about 1% on well-run crash games). Verification proves the result was random and unaltered — it does not change the odds. Anyone selling a "provably fair predictor" is selling a scam, because a committed, hashed result cannot be known ahead of time.
Frequently asked questions
What does provably fair mean?
A cryptographic system that lets a player verify a game result was fixed before the bet and not changed afterwards, using a hashed server seed, a client seed and a nonce. It proves honesty but does not remove the house edge.
How do I verify a provably-fair round?
Save the hashed server seed and your client seed before playing, record the result and nonce, then after seeds rotate hash the revealed server seed to confirm the commitment and recompute SHA-256(server:client:nonce) with the game formula to match the result.
Can a provably-fair game be predicted?
No. The outcome is cryptographically committed before the round, so it cannot be known in advance. Any predictor tool is a scam, and the house edge still applies.