How Provably Fair Games Actually Work
February 25, 2026
“Provably fair” is one of crypto gambling’s biggest selling points. Unlike traditional online casinos, where you have to trust the operator, provably fair games let you verify that each outcome was random. Here’s how it works.
The Basic Idea
Before a bet is placed, the casino generates a random seed and a hash of that seed. The hash is shown to you. After the bet, the casino reveals the original seed. You can run the same algorithm locally to confirm the outcome matches the seed—and that the seed wasn’t changed after the fact, because the hash would no longer match.
Client Seed + Server Seed
Most provably fair systems use two seeds: one from you (client) and one from the casino (server). The server seed is hashed before the round; you only see the hash. After the round, both seeds are revealed. You combine them (e.g. client_seed + server_seed) and hash the result to get the outcome. If the server had changed its seed after seeing your bet, the hash wouldn’t match—so you’d know something was wrong.
Where to Find It
BC.Game, Metaspins, Fortunejack, and TrustDice all offer provably fair dice, crash, and similar games. Each site has a “Provably Fair” or “Verify” button in the game interface. Click it, and you’ll see the seeds and the verification steps. Our provably fair crypto casinos list has the full comparison.
Does It Guarantee Fairness?
Provably fair proves the outcome was derived from the seeds—it doesn’t prove the house edge is what the casino claims, or that the RNG is cryptographically strong. But it’s a big step up from “trust us.” For players who care about verifiability, it’s a real advantage of crypto casinos.