Verify it yourself

    Four steps: paste the Server Seed, Client Seed and Nonce, choose the draw type and enter the Probability or Threshold, then press Verify. You’ll find this data in the platform’s draw history or fairness page.

    Enter Seeds

    Calculated only in your browser; nothing is uploaded.
    Optional: compare with the platform’s record

    Batch Verify

    Recalculate a run of Nonces with the same Seeds, up to 1,000 at a time. Fill in the Seeds above first. Results use the Probability entered above. Ichiban Kuji and Card Upgrade change probabilities every draw, so compare the Roll only.

    For platforms: integration docs

    What platforms need to publish, the algorithm, code samples and test vectors are all in the integration docs. Integration Docs

    How Provably Fair works

    The result is locked before the draw. After it, anyone can recalculate it.

    CommitBefore the draw

    The platform first publishes the Server Seed Hash, a hash of the seed. If the seed is swapped later, the hash won’t match.

    Server Seed Hash21ee8400600ae9f1…3c00aa2be5bb

    RollDuring the draw

    Each draw is calculated from the Server Seed, your Client Seed and the Nonce. The platform can’t see your seed and then change the result.

    HMAC-SHA256 · k7Qp2xVb:37:0Roll = 1,163,190,975

    RevealAfter seed rotation

    The platform reveals the old Server Seed. Press Verify and your browser recalculates the draw on its own.

    Server Seed452c4586d1c1fbb3…d1989d8c78e1d0

    FAQ

    About Provably Fair and this verifier.

    What is Provably Fair?

    Every draw can be recalculated from public data. Before drawing, the platform commits to a set of seeds and reveals them at rotation, so anyone can check whether a result was changed.

    What does the Server Seed Hash do?

    It is the SHA-256 hash of the Server Seed, published before the draw. The seed can’t be worked out from the hash, so players can’t see results before the seed is rotated. The seed the platform reveals later must produce the same hash. If it doesn’t, the seed was swapped.

    Why do I have to rotate the seed before I can verify?

    Once a Server Seed is public, every later draw under it can be calculated in advance. So the platform reveals the old seed only when it rotates seeds. Every draw under that seed can then be verified.

    What does the Client Seed do?

    The result also depends on your Client Seed. If the platform lets you set it, the platform can’t know which one you’ll use when it commits its seed, so it can’t arrange results in advance.

    How are Oripa and Ichiban Kuji probabilities calculated?

    Each prize has a weight, and its probability is its weight divided by the total. For Ichiban Kuji, the weights are the tickets left in each tier at the moment of the draw, so the probabilities change with every ticket drawn.

    Where do I find this data?

    In the platform’s draw history or fairness page: the Server Seed Hash published before the draw, your Client Seed, each draw’s Nonce, and the draw’s Probability or success rate. The platform only reveals the Server Seed after you rotate seeds.

    Is my data uploaded when I verify?

    No. Every calculation runs in your browser, and what you enter is never sent to a server.

    What does “Verified” mean?

    It means this draw was calculated from the seeds you entered and matches the platform’s record. Check the following against the platform’s record yourself: the Probability and fingerprint published before the draw, the Client Seed you set, whether any Nonce was skipped, and the prize you actually received. The platform sets the Card Upgrade success rate; JACKZ.AI only checks whether the Roll falls within the Threshold.

    What if verification fails?

    Take a screenshot of this page and send it, with the draw record and its ID, to the platform’s support.