Provably fair
Every Originals round at Duel can be recomputed from its seeds. Here is what that actually proves, what it does not, and how to check one yourself in about two minutes.
The problem it solves
At a traditional online casino you have no way of knowing whether a result was generated fairly. The random number generator runs on the operator's server, you cannot see it, and your only assurance is that a testing house audited it at some point. That is a reasonable assurance and it is still trust rather than proof.
Provably fair replaces the trust with arithmetic. The outcome is committed to before you bet, in a form you can check afterwards but not read in advance. Once the round is over, the commitment is revealed and anyone can confirm that the result matches — meaning it could not have been chosen after seeing your bet.
How the commitment works
Three inputs produce every result.
Server seed. Generated by the casino and kept secret during play, but its SHA-256 hash is published to you beforehand. A hash is one-way: you cannot derive the seed from it, but once the seed is revealed you can confirm it produces that exact hash. This is the commitment — the casino has locked in a value it cannot change.
Client seed. Supplied by you and changeable at any time. This is the part that matters most and the part players ignore. Because you contribute an input the casino did not know in advance, it cannot have pre-computed a sequence of results tailored against you.
Nonce. A counter that increments with each bet, so the same pair of seeds produces a different result every round.
The three are combined and hashed, and the output is mapped onto the game's outcome space — a multiplier for Crash, a number for Dice, a path for Plinko.
Verifying a round
Five steps, and the whole point is that step four does not involve the casino.
One. Before playing, note the hashed server seed shown in the game's fairness panel.
Two. Set your own client seed to something you choose rather than accepting the default.
Three. Play, and note the nonce of the round you want to check.
Four. Rotate the seed so the server seed is revealed. Now take an independent SHA-256 tool — any of them, not the casino's verifier — and confirm two things: that hashing the revealed seed reproduces the hash you noted in step one, and that combining the three inputs produces the result you were shown.
Five. If both match, that round could not have been manipulated. If either fails, you have found something genuinely worth reporting.
Using the operator's own verifier defeats the exercise entirely. A tool supplied by the party being checked proves only that the tool agrees with itself.
Crash and the drand beacon
Crash goes further than the standard scheme. Rather than relying only on a server seed the casino generates, it draws entropy from drand — a public randomness beacon operated by a distributed group of independent organisations, publishing a fresh unpredictable value at fixed intervals.
The consequence is that no party can influence a round even in principle. Under the standard scheme the casino generates the server seed, and while it cannot change it after committing, it did choose it. With a public beacon, the randomness comes from outside the system entirely and the operator has no more access to it than you do.
You can check a Crash round against the published beacon output for that round independently of anything Duel says. Mechanics are on the Crash page.
What it does not prove
This is where the term gets oversold across the whole category, so plainly:
It does not remove the house edge. A provably fair roulette wheel is provably a wheel with a house edge. Verification confirms the result was honest; it says nothing about whether the game favours you. Only the Originals at 100% have no edge, and that is a configuration choice rather than a consequence of being verifiable.
It does not cover third-party games. Slots from Pragmatic Play or Hacksaw are not provably fair — they are certified by testing houses, which is the traditional trust model. Only the in-house Originals publish seeds.
It does not mean you will win. A verified losing streak is still a losing streak, and variance on a zero-edge game routinely produces long runs in either direction.
It does not audit the operator's solvency. Fair results and the ability to pay a withdrawal are unrelated questions. The second one is covered on the withdrawals page.
Common misunderstandings
"The casino can still pick a favourable server seed." It can choose the seed, but it must commit to the hash before you play and it does not know your client seed. Changing your client seed regularly removes any theoretical benefit from a pre-selected server seed entirely.
"If I can verify results, I can predict them." No. Verification is retrospective and depends on the server seed being revealed, which happens only after the round. A hash is one-way; there is no path from the published hash to the outcome in advance.
"A losing streak proves rigging." It does not, and this is where most accusations come from. Long runs are ordinary at any edge including zero. The point of a verifiable system is that you can settle the question with arithmetic rather than argue about it.
"Provably fair means regulated." Unrelated. Provably fair is a technical property of individual games. Regulation is about capital requirements, dispute resolution and whether anyone can compel the operator to pay you. Duel is strong on the first and weak on the second — see the restricted countries page for why the licence is what it is.
Why bother
Most players never verify a round, and the system works anyway — because it only takes a handful of people checking for a manipulated result to be discovered. The value is not that everyone verifies; it is that anyone can, which makes manipulation a strategy that fails on discovery.
That is a materially different assurance from a certificate on a footer, and it is the strongest thing on this casino's record. The methodology page covers how many rounds we checked and how.