# Provably Fair Verifier — Check a Casino Seed & Roll Yourself > Free provably-fair verifier. Check that a casino’s revealed server seed matches the hash it committed to before you played, and recompute a roll from server seed, client seed and nonce. Runs in your browser — nothing is uploaded. Source: https://tekeldata.com/tools/provably-fair-verifier · Publisher: Tekel Data (tekeldata.com) · Last updated: 2026-08-21 License: CC BY 4.0 — reuse with attribution. Live data API: https://tekeldata.com/mcp (MCP, keyless) · https://tekeldata.com/llms.txt --- [Home](https://tekeldata.com/) / [Guides](https://tekeldata.com/guide) / Provably fair verifier # Provably fair verifier Last updated: 2026-08-21 · live on-chain data, refreshed ~every 30 min Two checks, both running entirely in your browser. Nothing you paste is uploaded, logged or sent to us — a server seed is a live credential until the operator rotates it, so it should never leave your machine. ## 1. Did the casino commit to the seed before you played? This is the check that actually matters, and it works the same way at every provably-fair casino. Before your session the operator shows you a hash of its server seed. Afterwards it reveals the seed itself. If the revealed seed hashes to the value committed beforehand, that seed could not have been swapped after seeing your bets. If it does not, nothing else about the game is worth checking. Revealed server seedHash shown before you played — optional, leave blank to just compute the hash ## 2. Recompute a roll from the seeds Most crypto casinos derive each result from HMAC-SHA256(server seed, client seed:nonce:cursor), take the first four bytes of the digest and turn them into a float in [0,1). That float becomes the dice roll, the crash multiplier, the card index. The tool below implements that widely-used scheme, so you can reproduce one specific bet and see the arithmetic rather than trust a screenshot. Server seed (revealed)Client seedNonce (bet number) ## What this proves, and what it does not A passing commitment check proves one specific thing: the server seed was fixed before your bets. That rules out the crudest cheat — an operator choosing the seed after seeing what you wagered. It is a real guarantee, and it is worth checking. It does not prove the operator is solvent, that it will process your withdrawal, or that the advertised house edge is what the game actually pays. Those are separate questions with separate evidence: reserve balances anyone can read on a block explorer, observed withdrawal flow, and the complaint record. A casino can run mathematically perfect games and still fail to pay — the two properties are unrelated, which is exactly why we publish reserve and flow data alongside this tool. See [provably fair explained](https://tekeldata.com/guide/provably-fair-explained) for the mechanics in full, and [proof of reserves](https://tekeldata.com/proof-of-reserves) for the solvency side. One caveat on the second tool. The commitment check is universal; the float derivation is not. The scheme above is the common one, used by Stake-style implementations and the many casinos that copied it. An operator using a different message format, byte count or cursor convention will produce a different number here — that is a difference in scheme, not evidence of cheating. ## Frequently asked Can a provably fair result be predicted? Not without the server seed, which the operator only reveals after that seed pair is retired. Anyone selling a "predictor" for an unrevealed seed is selling nothing — the whole scheme rests on that seed staying secret between commitment and reveal. Does provably fair mean a crypto casino is safe? No. Provably fair is a guarantee about game outcomes only. Solvency, withdrawal behaviour and licensing are separate questions with separate evidence. An operator can run mathematically perfect games and still fail to pay. Does this verifier store or upload my seeds? No. Both checks run in your browser using the Web Crypto API — no network request, and no analytics on the inputs. A server seed is a live credential until the operator rotates it, so it should never leave your machine. You can confirm this in your browser devtools network tab while using the page. The recomputed roll does not match what the casino showed. Is that cheating? Usually not. The seed-commitment check is universal, but the float derivation is not: operators vary the message format, the number of bytes taken and the cursor convention. A different number here means a different scheme, not evidence of cheating. Check the operator’s own fairness documentation for its exact formula. [Provably fair explained](https://tekeldata.com/guide/provably-fair-explained) · [RTP & house edge](https://tekeldata.com/guide/crypto-casino-rtp-and-house-edge) · [Verify an operator on-chain](https://tekeldata.com/guide/how-to-verify-a-crypto-casino) · [Proof of reserves](https://tekeldata.com/proof-of-reserves) Methodology & disclaimer. Figures are derived from on-chain transfers attributed to wallets we associate with each operator, plus third-party ratings shown with their source. Blockchain attribution carries inherent uncertainty, and reserves are an all-chain best-effort estimate from mapped wallets — coverage varies by operator. These pages describe observed activity and third-party data only; they are not an endorsement of any operator and not a statement on any operator's solvency, legality, fairness, or safety, and nothing here is financial, legal or investment advice. See [how we attribute on-chain activity](https://tekeldata.com/methodology/address-attribution) · [about us](https://tekeldata.com/about) · [report a correction](https://tekeldata.com/app). Data updates roughly every 30 minutes. 18+ only. Gambling can be addictive — see [responsible gambling resources](https://tekeldata.com/responsible-gambling). Cite this page. Tekel Data, “Provably Fair Verifier — Check a Casino Seed & Roll Yourself”, 2026-08-27, [https://tekeldata.com/tools/provably-fair-verifier](https://tekeldata.com/tools/provably-fair-verifier) — figures are on-chain observations as of that date and change as the chains do. Reuse permitted with attribution (CC BY 4.0). Machine-readable: [markdown](https://tekeldata.com/tools/provably-fair-verifier.md) · [MCP](https://tekeldata.com/mcp.json) · [llms.txt](https://tekeldata.com/llms.txt).