Fairness
Provably fair: check a round yourself
The round's multiplier is determined by the trio server seed + client seed + nonce. Below — what this means, how to recheck any round step by step, and three working tools: a verifier, a distribution generator, and a calculator. Everything is computed in your browser, no data goes anywhere.
'Fair' isn't something you have to take on faith. In crash games, fairness can be verified mathematically: each round comes with a cryptographic proof that any player can recompute on their own. Let's break down how this works and provide the tools to verify it personally — right on this page.
What provably fair is
Provably fair ('provably honest') is a mechanism that prevents the casino from changing the result after the fact. It's built on two ideas: a commitment before the round and a reveal after.
- server seed — a secret random value on the server side. Before the round, only its hash is published.
- client seed — your contribution: a value on your side that also affects the outcome.
- nonce — the round number, so that the same set of seeds gives different results.
The round's multiplier is computed as a function of these three values via the SHA-256 hash function. Since the hash of the server seed is published in advance and is irreversible, the casino can't substitute a different seed after seeing the bets. And since your client seed is also part of the formula, it can't 'fit' the seed to the desired outcome in advance either. No one controls the result alone — that's the whole point.
How to check a round
Checking any round comes down to a few steps:
- Before the round, save the published hash of the server seed.
- After the round, take the revealed server seed, your client seed, and nonce.
- Compute SHA-256 of their combination and make sure the hash of the server seed itself matches the one published in advance.
- Derive a number from the hash and convert it to a multiplier — it should match what the game showed.
The specific multiplier formula looks like this (for a return of 97%). It can be reproduced in any language — here's a reference in Python:
The distribution of multipliers also follows from this formula: the probability of reaching ×x is approximately 0.97/x. Below you can verify this yourself.
Round verifier
Enter the values — the browser will compute SHA-256 and output the multiplier. This is the same math as the casino's: identical inputs give an identical result.
Round verifier
Everything is computed locally and offline — no data is sent anywhere.
———Build your own distribution
Generate many rounds with different nonces and see how often multipliers are reached. The observed shares will be close to the theoretical 0.97/x — and the closer, the more rounds.
Distribution generator
Each run takes a random server seed and computes the chosen number of rounds.
The more rounds you set, the closer the observed shares are to theory — that's the law of large numbers in action.
RTP and edge calculator
See how the return and the cash-out point affect the casino's edge, the expectation, and the spread. Note: by changing the cash-out target, you change the chance and the spread, but the casino's edge stays the same.
Return calculator
The expectation is computed for a flat bet with cash out at a set multiplier.
——————Key point
Verifiability protects against deception, but not against math
Provably fair is a powerful tool: it guarantees that the casino doesn't tweak rounds, and you can prove it yourself. But that's exactly why it leaves no loopholes for the player either: a fair distribution still contains the casino's edge. Verifiable fairness and profitability are different things.
Bottom line: provably fair makes the game transparent and protects you from tweaking — that's genuinely valuable. But transparency works both ways: it also shows that a fair distribution can't be beaten. It's precisely on the misunderstanding of this that 'predictors' and paid 'signals' make money — why they're impossible is covered in the next article.
Frequently asked questions
It's a way to make sure the casino didn't tweak the result, without taking its word for it. Before the round, the server publishes a hash of the secret server seed (a commitment). The outcome is computed from this server seed, your client seed, and the round number. After the round, the server seed is revealed — and you recompute the multiplier yourself and check its hash against the one published in advance. A match means the result wasn't changed after the fact.
A hash function (here SHA-256) turns any data into a fixed-length string in such a way that it's practically impossible to recover the original data from the result and impossible to find other data with the same hash. So the casino, having published the hash of the server seed in advance, can't then 'change its mind' and substitute a different seed: any other seed would give a different hash, and the substitution would immediately come out on verification.
The client seed is your contribution to the result. Since the outcome depends on it too, the casino can't prepare a 'convenient' server seed for a specific outcome in advance without knowing your client seed. In many games the client seed can be changed. This protects against collusion: neither side controls the result alone.
Because provably fair guarantees fairness and verifiability, but not profitability. The casino's edge is built into the very distribution of multipliers (a return of about 97%), and it acts equally fairly for everyone. Verifiability protects you from tweaking and deception, but it doesn't cancel the negative expectation over the distance. A fair game and a profitable game are different things.
Yes. The verifier uses a real SHA-256 implementation right in your browser: the same server seed, client seed, and nonce will give the same hash and the same multiplier as a casino with the same formula. Everything runs locally and offline — no data is sent anywhere. This is a demonstration of the principle on honest math, not a simulation.