Guide · Provably fair on-chainUpdated 9 October 2026

Guide

74provably fair originals at BC.Game

Provably Fair On-Chain: what a seed and a contract prove

With provably fair, one bet can be checked once it settles: the casino commits to a server seed, you contribute a seed as well, a nonce counts each bet, and once the seeds change you can check the result. On-chain means something else: the money, the random number, or both are stored in a readable contract. This guide separates the two and lists what is published casino by casino.

1,000bets before Just.bet rotates a seed on its own
2random-number contracts Metawin names for its draws

Where it appliesOn-chain casino rankingThe ten scored on what settles on the chain.

On-chain casino ranking

Check a bet

Provably fair on-chain: BC.Game's home page, 8 October 2026, the casino whose originals shelf counts 74 games with provably fair seeds — BC.Game, 8 Oct 2026

What a provably fair bet proves, step by step

3inputs: server seed, client seed, nonce
1hash published before the bet
0chains involved in the check itself

The commitment

The casino publishes the hash of its server seed before each bet: a fingerprint which reveals nothing about the seed, but changes if and when the seed changes. The fairness page of BetFury publishes the hash before the bet and the seed after; Bitcasino's Originals do the same. The seed cannot change without the hash giving it away.

Your part

You set a client seed, and a nonce counts each bet. The result is computed once the three elements are combined. Just.bet's review names the function, an HMAC-SHA256, and the rotation rule: on its own after 1000 bets or on request.

The reveal

When the seed pair rotates, the old server seed is shown. Hash it and match it with the fingerprint you saw before starting the game. Re-compute the bet with seed, client seed, and nonce and match it with the result you got. Solcasino’s review describes a verification tool that confirms the result after the seed pair rotation; and this can be done with any SHA-256 hash tool.

Checking one bet at any of the five that publish seeds

Open the fairness page before you play. BetFury, Bitcasino, Solcasino and Just.bet each name one on their reviews; BC.Game's originals show their seeds in the game. Copy the current server seed hash.
Set your client seed. Any value. A seed you chose is the proof the pair was not fixed by the casino alone; a default one is weaker but still yours.
Play, and note the nonce. Each bet gets the next number. To check bet 37, you will need the nonce 37 and the same two seeds.
Rotate the seed pair. The fairness page reveals the old server seed and shows the hash of the next one. Just.bet rotates on request or after 1,000 bets on its own; the others rotate on request.
Recompute. Hash the revealed seed and compare it with the hash you copied; then run the casino's verifier, or any HMAC-SHA256 tool, with seed, client seed and nonce, and compare with the result you got.
Keep the two results. A match proves the bet was decided by the committed seed. A mismatch is a documented complaint, with the hash, the seed and the nonce as the evidence.

Where a contract takes the seed's place, and where it does not

Metawin's draws: a contract and a named random source. Entries are captured in a smart contract. Ethereum draws use Chainlink’s verifiable random function and Base draws use API3’s QRNG, according to the Metawin review. The winner is picked by a number the contract received with a proof. The entry record is readable on chain. This is only applicable for prize draws; Metawin’s slots and live games are studio games (independently tested).

Just.bet: seeds on the server, money in a contract. The terms state the outcomes are decided off-chain with an HMAC-SHA256 commit-and-reveal scheme. This is not recorded on a blockchain. The contract holds the balance of the player (in escrow) on Arbitrum and withdrawal is done with a Merkle proof. Here, the seed is checked for fairness; the blockchain is for the money.

Nothing on this site draws a slot on-chain. No reviewed casino employs a studio slot with a contract. Also, no reviewed casino pays a slot win with a contract. The Web3 slots ranking says so for every one of them, and the on-chain ranking scores what they do instead.

What each of the ten publishes

5casinos publishing seeds
1casino with a contract-drawn game: Metawin's draws
4casinos with no fairness page found

Casino	What is provably fair	How to check it	As stated where
BC.Game	74 originals with provably fair seeds: Crash at a published 99% return, Plinko, Limbo, Keno, Mines, Dice, Wheel, Blackjack, Roulette, Baccarat	Seeds in the game; slots and live games are studio games the FAQ calls independently tested	BC.Game review
BetFury	24 originals	A hash published before the bet and the server seed after it; the fairness page walks through the SHA-256 check	BetFury review
Bitcasino.io	The Bitcasino Originals	Each round commits to a server seed hash, uses your client seed and a nonce, reveals the seed afterwards; a verifier guide in the help centre	Bitcasino review
Solcasino	The house originals	A hashed server seed before the bet, your client seed, a nonce per bet, a verification tool once the seed pair is rotated	Solcasino review
Just.bet	Every game, on the server	A server seed per account with its SHA-256 hash published; HMAC-SHA256 commit and reveal; rotation on request or after 1,000 bets; outcomes not recorded on a blockchain, by its terms	Just.bet review
Metawin	The prize draws, by contract; not the slots	Entries in a smart contract; Chainlink VRF on Ethereum, API3 QRNG on Base; slots independently tested, by the FAQ	Metawin review
Roobet	No fairness page found on the site	14 originals listed; no seed page found	Roobet review
Dexsport	No fairness page found on the site	48 studios, 7,700 games on the counter; studio games throughout	Dexsport review
Rollbit	No fairness page found on the site	X-Roulette and X-Crash are house games; no seed page found	Rollbit review
Fairspin	No fairness page found on the site	The earlier chain record is gone from the site; TFS rakeback remains	Fairspin review

Wording as each casino's own fairness page, FAQ or terms states it; a row that says none was found is not a finding against the casino.

What a seed check proves, and what it cannot

A matching check proves

This bet's result came from the server seed the casino committed to before you played
The casino did not change the result after seeing your bet: the hash would not match
The whole sequence of bets under one seed pair can be reproduced from the three inputs
A dispute has evidence: the hash, the revealed seed, the client seed and the nonce

It does not prove

That the odds are fair: the house edge is the game's design, published separately or not at all
That the server seed was random: only that it was fixed before the bet
That a studio slot is covered: provably fair applies to the originals at every casino here
That the win is paid: the balance sits where the custody guide says, and the seed has no say in it

The right-hand column is the reason this site evaluates custody, license and withdrawal terms on every review together with the fairness wording and the reason the rug-pull guide exists.

Provably fair questions players ask

What does provably fair mean?

That one bet can be checked against a commitment the casino made before it. The casino publishes the hash of a server seed, you set a client seed, a nonce counts each bet, and the result is a function of the three. After the seeds rotate, the server seed is revealed, and anyone can recompute the hash to confirm it was the committed one and recompute the bet to verify the result. Solcasino’s review puts it in one sentence; a hashed server seed is published before the bet, you control the client seed, a nonce counts each bet, and a verification tool checks the result once the seed pair is rotated.

How do I verify a provably fair bet?

Note the server seed hash before you play, set or note your client seed, play, note the nonce of the bet you want to check, rotate the seed pair so the server seed is revealed, then use the casino’s own tool to verify the result: Bitcasino keeps a verifier guide in its help center, BetFury’s fairness page walks through the SHA-256 check, Solcasino offers a verification tool, Just.bet publishes each account’s server seed hash and reveals the seed upon rotation. The steps section above outlines this.

Is provably fair the same as on-chain?

No. With Provably Fair, the casino keeps the server and the seed is fixed in advance. Just.bet's T&C explicitly state that their outcomes are not recorded on a blockchain. On-chain means the randomness is supplied by a smart contract, as is the case with Metawin's prize draws, which use Chainlink's VRF on Ethereum, or the money is held by one, as with Just.bet's escrow. The on-chain vs custodial guide covers the escrow.

Are slots provably fair?

Not at any of the ten reviewed casinos. Provably fair applies to a casino’s own games (originals, Crash, Plinko, Dice, Mines, etc). Slots by studio providers (Pragmatic Play, Play’n GO, etc) run on the studio’s RNG. Metawin’s FAQ states that their slots and live games are independently tested; BC.Game states the same for their outside games. Neither provide a report, so this site repeats the wording and no more.

What is a server seed and a client seed?

The server seed is a secret value the casino generates and commits to by publishing the hash; the client seed is a seed you set, so the casino cannot know it in advance. Just.bet generates a server seed for each account, publishes the hash via SHA-256 (per their review), and rotates it after 1,000 bets or upon request. A bet increases a nonce, which is used to ensure uniqueness for each outcome.

What is Chainlink VRF?

The Chainlink network delivers a random number and proof that the number was generated correctly to a smart contract. This site names it only as Metawin states it, for its Ethereum prize draws. Metawin’s Base draws use API3’s quantum random number generator. The casino games at Metawin are not drawn this way.

Does provably fair mean the odds are fair?

No. It proves the result came from the committed seed, and the game’s design determines the odds, and the house edge is published separately. BC.Game does this with Crash, which is set at a 99% return. A game can be Provably Fair and keep 5% of every bet over time. The approve-and-reject lists keep the two claims separate.

Which of the ten casinos are provably fair?

According to their sites: BC.Game has 74 originals, BetFury has 24 originals, Bitcasino Originals, Solcasino’s originals and every game offered by Just.bet, with Metawin’s prize draws determined by contract. No fairness pages were found for Roobet, Dexsport, Rollbit or Fairspin, and this site makes no claim for them.

The ten casinos, each with its fairness wording on its review

Keep reading

Elias Varga, CryptoReel editor, in Lisbon

About the author

Elias Varga writes CryptoReel from Lisbon. He names the fairness page or the random-number source exactly as each casino states it, and where none can be found he writes that rather than assuming a casino has one.

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