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Verify a bet

Provably fair calculator and verifier

Recompute a result from the server seed, client seed and nonce. Everything runs on your device.

Pick a casino, then what you want to check

Casino

Aviator roundAviator roundThree client seeds and one server seed give the multiplier of a finished flight.HMACOne bet from its seed pairServer seed, client seed and nonce rebuild a single dice-style result on this page.×NA whole list of betsPaste many finished bets and get one verdict for each line.

Nothing you paste leaves this page.

What you get

A check that the revealed server seed matches the hash you were shown before the bet, and the result recomputed from the three values.

Server seed, client seed and nonce: what each value is

  1. Server seedChosen by the casino and shown only as a hash until you rotate it.
  2. Client seedChosen by you. You can change it at any time.
  3. NonceCounts your bets on the current seed pair, starting from 0.

How a provably fair check works

Before you bet, the casino shows the SHA-256 hash of its server seed. After you rotate the seed pair it reveals the seed itself. Hashing the revealed seed must give the same hash.

SHA-256(server seed) = hash shown before the bet
result = f( HMAC-SHA256(server seed, client seed : nonce) )

Aviator joins three client seeds and has a formula of its own, so use the Aviator round verifier for it. A whole bet history can be pasted into the bulk verifier. The words on this page, from server seed to nonce, are explained in the glossary of provably fair terms.

Can a seed check predict the next result?

No. The server seed of a live pair stays hidden until you rotate it, so the one value the formula needs does not exist for you yet. This page only works backwards: it rebuilds a bet that is already finished. Anything sold as a seed predictor is guessing, and the guide to predictors shows why.

Questions about provably fair verification

Why can I not verify a bet right away?

The server seed stays hidden while it is in use. Rotate the seed pair and the casino reveals it.

Does a matching result mean the game is fair?

It means the result was fixed before your bet and was not changed. The house edge still applies.

Why do casinos need separate formulas?

They all hash the same three values, but each turns the hash into a game result in its own way.