Provably fair is a specific cryptographic system, not a marketing label. A provably fair casino must: 1. Commit to the game result before the player bets (using a cryptographic hash). 2. Allow the player to contribute randomness (client seed). 3. Reveal the server seed after the game so the player can verify. 4. Use a deterministic algorithm (like HMAC-SHA256) that anyone can reproduce. If a casino calls itself "provably fair" but doesn't provide all four elements, it's not provably fair — it's just claiming to be fair, which is what every casino does.

Not all implementations are equal: Level 1 — Server-side verification only: The casino provides a verification page, but you can't run the algorithm yourself. You're still trusting them. (Common at many "provably fair" casinos.) Level 2 — Open algorithm: The casino publishes the algorithm and lets you verify with your own code. Better, but you still trust that the commitment was made before your bet. (Stake, BC.Game, CryptoGames.) Level 3 — Blockchain-committed: The result hash is recorded on a public blockchain before bets open. Anyone can verify the timing independently. (AlgoRoll — commitments on Algorand.) Level 3 is the only implementation that eliminates all trust requirements.

Regardless of which casino you play at, here's how to verify: 1. Before playing, note the commitment hash displayed. 2. After the game, collect: server seed, client seed, and nonce. 3. Run: HMAC-SHA256(server_seed, client_seed:nonce) 4. Map the resulting hash to a game outcome using the casino's published algorithm. 5. Compare to your actual game result. If they match, the game was fair. If the casino doesn't give you all three inputs, or doesn't explain the mapping algorithm, it's not truly provably fair. AlgoRoll provides code examples in JavaScript, Python, and CLI, plus an on-site verification tool.

Here's how the major provably fair casinos compare: • AlgoRoll: HMAC-SHA256 + Algorand on-chain commitments. Verification page + code examples. 5 games. USDC stablecoin. 3.3s settlement. • CryptoGames: SHA-256 hash. Server-side verification page. 9 games. Multiple cryptos. Variable settlement. • PrimeDice: SHA-256 hash. Open algorithm. 3 games. Multiple cryptos. Variable settlement. • Stake/BC.Game: Claim provably fair on select games. Larger game libraries but most games use traditional RNG, not provably fair systems. The key distinction: AlgoRoll is the only platform with blockchain-committed results and full self-custody support.

Without blockchain commitments, provably fair relies on a subtle trust assumption: you have to trust that the casino committed the result before your bet, not after. The casino shows you a hash, but when was it generated? Blockchain commitments solve this. When AlgoRoll records a result hash on Algorand before the betting window opens, that transaction has a public, immutable timestamp. You can look it up on any Algorand block explorer. No trust required — the timing is independently verifiable.