“Provably fair” is a crypto casino feature that lets you check, after a bet, that the result wasn’t changed once you placed it. It’s a genuinely useful idea, and also one that’s often oversold. This guide explains how it works, how to verify a bet yourself, and what it does and doesn’t prove.
The problem it solves
With an ordinary online game you have to trust that the casino didn’t pick the outcome after seeing your bet. Provably fair games use cryptography so the casino commits to the outcome’s ingredients before you bet, in a way it can’t change later without you noticing.
How it works
The details vary by casino, but most in-house games use the same three ingredients:
- Server seed. The casino generates a secret random value. Before you bet, it shows you only its hash, usually SHA-256: a fingerprint that can’t be reversed to reveal the seed.
- Client seed. You supply (or can change) a value of your own, so the casino can’t pre-compute results that suit it.
- Nonce. A counter that goes up by one with each bet, so every bet with the same pair of seeds gets a different result.
The game combines the three to produce the result. When you rotate to a new server seed, the casino reveals the old one. You can then hash it yourself and check it matches the fingerprint you were shown at the start, and recompute every result from the seeds and nonces.
Try it: what a hash commitment looks like
This box computes the SHA-256 hash of whatever you type, in your browser. Change one character of the seed and the hash changes completely. That’s why a casino can’t swap the seed after showing you its hash.
Some casinos use a variation for multiplayer games like Crash: they generate a long chain of hashes in advance and play it in reverse order, so each round’s result is fixed before anyone bets. BC.Game, for example, explains this approach in its help centre.
How to verify a bet
- Before playing, note the hashed server seed shown in the game’s fairness settings, and set your own client seed if you like.
- Play, then rotate the seed. The casino reveals the previous server seed.
- Check the hash. Hash the revealed seed (the box above works for SHA-256) and compare it with the one you noted.
- Recompute a result. Use the casino’s verifier, or an independent one, with the server seed, client seed and nonce. The result should match your bet history.
What provably fair doesn’t prove
- It doesn’t remove the house edge. A provably fair dice game with a 1% edge still keeps 1% of everything wagered on average. Fair means unmanipulated, not favourable.
- It usually covers only in-house games. Slots and live tables from outside studios rely on their own random number generators and testing, not seed verification.
- It doesn’t guarantee payment. A casino can run perfectly fair games and still refuse a withdrawal. Licences, terms and complaint records matter more; see our reviews.
- You have to actually check. The protection only works if someone verifies. Spot-checking a few bets now and then is enough to make cheating risky for the casino.
Provably fair at the casinos we’ve reviewed
| Casino | Provably fair games |
|---|---|
| Cloudbet | Yes: 8 Cloudbet Originals (Mines, Plinko, Dice, Limbo and more) |
| Shuffle | Yes: 17 Shuffle Originals plus SHFL Lotto |
| Roobet | Yes for Crash; not stated for other house games |
| Bitcasino.io | Yes: Bitcasino Originals (e.g. Original Blackjack) |
| Duelbits ⚠ | Yes: Duelbits Originals such as Crash, Dice, Mines and Plinko |
| Wild.io | Yes: a provably fair category with Wild Originals such as Dice, Mines, Plinko and Crash |
| Stake | Yes: Stake Originals such as Dice, Plinko, Crash, Limbo and Mines |
| Winz.io | Yes, according to its FAQ; titles not listed |
| Thunderpick ⚠ | Yes: Thunderpick Originals such as Thunder Mines, Dice and Limbo |
| Metaspins | Yes, by its own description: Metaspins Originals such as Dice, Mines, Plinko and Crash |
| BitStarz | Yes: 13 BitStarz Originals |
| Rollbit ⚠ | Yes: Rollbit originals such as X-Crash, X-Roulette and Plinko |
| BC.Game ⚠ | Yes: BC Originals such as Crash, with a verifiable hash chain |
| TrustDice ⚠ | Yes: in-house games such as Dice, Crash and Plinko |
| BetFury | Yes: 20+ BetFury Originals (Dice, Crash, Plinko, Mines and more) |
| 1xBit ⚠ | not stated |
FAQ
Are provably fair games better odds?
Are slots provably fair?
Can a casino cheat at a provably fair game?
Checked October 2026. Casino details from our reviews, each with its own sources; Crash hash-chain example from BC.Game’s help centre.