Fairness
Provably fair
A provably fair round is one you can recompute yourself. The operator commits to a secret before you play, you supply a value of your own, and once the secret is revealed anyone can rebuild the result and check that it was never changed.
The short answer
Provably fair means the outcome of a round is derived from three values you can inspect: a server seed the operator commits to before you play by publishing its hash, a client seed your own browser supplies, and a nonce that counts the rounds. Run those three through the game's published algorithm and you get back the result the game paid you, every time, on any machine.
The proof is retrospective, never live. You cannot see the server seed while it is in use, or outcomes would be predictable; you see its hash. When the seed is retired it is revealed, and hashing it has to reproduce the commitment you were shown. If it does not, the seed was swapped, and every round played under it is suspect.
It does not cover the whole site, and no honest operator claims otherwise. Provably fair applies to the in-house originals, where the operator writes the maths and can publish it. It does not apply to third-party studio titles — slots, live dealer tables, game shows — which run on the studio's own certified generator and expose no seed for anyone to check. Both kinds sit in the same lobby. They are not the same guarantee.
The three values a round is built from
Two of them are known to you before the round settles. The third has to be revealed afterwards for the proof to close.
Server seed
A random secret generated on the operator's side. You never see it while it is live — you see its hash, published before your first round under it. That hash is the commitment: it pins the seed down without disclosing it, because hashing runs one way only and no second seed produces the same output.
Client seed
A value from your side, editable in the game's fairness panel. It exists so that a committed seed cannot also be a chosen one: the operator cannot select a server seed with a convenient outcome when half the input is a value you set independently, afterwards, and can change whenever you like.
Nonce
A counter that increments by one on every round. Same server seed, same client seed, a different nonce: a different outcome, and one that can be checked round by round rather than only in bulk. It is what lets a single pair of seeds cover a whole session.
How a round is verified, in four steps
Verification happens after the fact, on your own machine, using values the game hands you. It needs no account access and no cooperation from us beyond publishing the algorithm — which is the entire point of the arrangement.
Copy the commitment
Before you play, the fairness panel shows the hash of the server seed currently in use. Copy it and keep it. It is the only thing that has to come from before the round; everything else can be read afterwards.
Play the rounds
Each round consumes one nonce, and the panel shows your client seed and the current nonce while you play. So at the moment a round settles you already hold two of its three inputs, plus the commitment to the third.
Rotate the seed
Rotating retires the server seed and reveals it. Nothing is verifiable until that happens, which is why a seed you never rotate is a seed you never checked. Once revealed, it cannot be used for any further round.
Recompute and compare
Hash the revealed seed: it has to equal the commitment you copied. Then feed the seed, your client seed and the nonce through the published algorithm and check that the outcome matches what you were paid. The algorithm is public, so you can use an independent verifier rather than one of ours.
Where the proof applies, and where it does not
Covered
In-house originals
Games where the operator writes the maths and can therefore publish it: the fast-round formats — crash curves, dice, mines, wheels, plinko-style drops. One nonce per round means verification is per round rather than per session, so a single suspicious result can be checked on its own.
These sit mainly under Crash and Instant win, where a round lasts seconds and the outcome is a single number rather than a reel spin.
Not covered
Third-party studio games
Slots, live dealer tables and game shows built by outside studios. Their outcomes are produced inside the studio's own engine, on the studio's servers. The studio does not hand out a seed, and no operator can make it. A casino that markets its entire lobby as provably fair is describing something that does not exist.
What these titles carry instead is certification: an independent test house examines the random number generator and the published return to player, then re-tests it periodically. That is a real control. It is also a different one — an audit you trust, rather than a proof you run.
Live dealer games are a third case again. The randomness there is a physical wheel or a real deck in front of a camera, so there is no seed to publish and nothing to hash. What you verify on those tables is what you can see.
What provably fair does not prove
This is the part most pages on the subject leave out, and it is the part that decides how much the claim is actually worth to you.
- It says nothing about the odds
- A game with a one per cent house edge and a game with a ten per cent house edge can both be provably fair. Verification confirms the result was not altered after the fact. It passes no comment on the terms you accepted before it.
- It does not change your expected return
- Return to player is a property of the paytable, not of the seed. A verified round is a verified round, and a hundred verified losing rounds are still a hundred losing rounds. Fairness here is a statement about process, never about outcome.
- It is worth nothing unverified
- Almost nobody checks, and a proof nobody runs protects nobody in particular. What it does protect is everybody in general: the operator has to behave as though someone will check, because any single player can, at any time, on any round.
Proof of a round and proof of a payment are two different guarantees, and only the second one lives on a public network. A deposit and a withdrawal are ordinary transactions that anyone holding the hash can read in an explorer; a round is settled on a server and proved by commitment instead, with nothing written to a block. What actually runs on-chain at a blockchain casino
Three habits that make the proof usable
- Set your own client seed before you play rather than after. A default seed still works, but you are then trusting that it was not chosen for you, which is precisely the trust the scheme exists to remove.
- Rotate the server seed at the end of a session, not only when something looks wrong. Rotation is what reveals the seed, and a batch of rounds you never revealed is a batch you can never check.
- Record the commitment hash off the screen while it is still live. A hash you read afterwards proves nothing at all: the whole force of it comes from having been published before the outcome existed.