Provably fair is a cryptographic mechanism that lets a player verify for themselves that a round's result was fixed before the bet was placed and was not changed afterwards.
How it works
Before the game the casino shows the hash of the server seed — a fingerprint that binds the casino to the result formula without revealing the result itself. Each round's result is calculated from three parts: the server seed, your own client seed and the bet's sequence number. When the seeds are rotated, the casino reveals the old server seed and you can check whether its hash matches the one you were shown before the game. If it matches, the result was locked before your bet.
What it covers and what it does not
Provably fair confirms exactly one thing: the result of that particular round was not manipulated. It says nothing about withdrawal speed, bonus rules, customer support or the licence — a casino with honest maths can still drag out a withdrawal or void a bonus through the small print. Those things have to be assessed separately.
What to check
- Whether the casino has a real verification tool and instructions, not just a "provably fair" logo. - Whether you can set the client seed yourself and rotate the seeds. - Whether the old server seed is revealed after a rotation. - Which games it applies to at all: the mechanism is common in the casino's own crash, dice and mines-type games. Ordinary video slots have their results generated by the provider's RNG, checked by external auditors — there is no seed pair there.
Together with RTP it gives a complete picture of a game's maths. Where each casino stands on this is set out in the ranking.