Provably fair
Provably fair describes games whose results you can check yourself using cryptography. The casino commits to a hashed server seed before you bet, your client seed and a counter are mixed in, and after the seed is revealed you can recompute and confirm every result.
By Mark SmithChecked Provably fair is a system that lets players verify game outcomes themselves, instead of relying only on a casino’s word or a lab certificate. It’s most common in crash games and crypto casino games.
It works with three ingredients:
- A server seed, chosen by the casino. You’re shown its SHA-256 hash before you bet, which locks it in.
- A client seed, which you can set or change.
- A nonce, a counter that goes up with each bet.
The game combines these (usually with HMAC-SHA256) to produce the result. When the server seed is later revealed, you can hash it to check it matches what you were shown, then recompute the result. If both match, the casino couldn’t have altered the outcome after seeing your bet.
Games like Aviator, Mines and Plinko work this way. You can check a round with our provably fair verifier.
What provably fair doesn’t do: it doesn’t lower the house edge, and it doesn’t guarantee a casino will pay out. Licensing and reputation still matter. The full walk-through is in how provably fair works, and you can browse provably fair games.
Frequently asked questions
What does provably fair mean?
It means a game uses a published cryptographic method that lets you verify each result wasn't changed after you placed your bet.
Which games are provably fair?
Most crash games, including Aviator, plus Mines, Plinko, Dice, Hi-Lo and many crypto casino originals. Traditional slots usually use certified RNGs instead.
Does provably fair mean better odds?
No. It proves fairness of each result, not the size of the house edge. A provably fair game still has an RTP below 100%.
Related terms
Mark has been writing about online gaming since 2007, covering everything from sportsbooks to casino and slot reviews, offering insights for players of all levels.