The underlying concept of provably fair is that players can prove and verify that every result is fair and unmanipulated. This is achieved through a commitment scheme combined with cryptographic hashing.
The commitment scheme ensures that you have influence on all results. Cryptographic hashing ensures that the server also remains honest. Both combined create a trust-less environment.
This is simplified in the following representation:
fair result = server seed (hashed) + client seed
How It Works
1
Before you play — The server commits to a secret seed by showing you its SHA-256 hash. It cannot change the seed after this point.
2
You play — The deck is shuffled using HMAC-SHA256(server_seed, client_seed:nonce). Your client seed is something you control, so the server cannot predict or rig the outcome.
3
After the game — The real server seed is revealed. You can hash it yourself and confirm it matches the commitment shown before you played.
4
Verify — Plug the three values (server seed, client seed, nonce) into the Verify tab. It re-derives the full deck in your browser — no server contact.
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🎲 What Are the Odds?
To win, you must guess correctly across 5 stages in a row. Each stage narrows the deck further.
StageYour GuessBest Odds
1Red or Black?50%
2Higher / Lower / Between?72.4%
3Higher / Lower / Between?54.9%
4Pick a Suit (♣♦♥♠)26.5%
5Exact Card~2%
Overall chance to win
0.1099% · 1 in 909.83
💡 Tip: Always pick the option covering the most remaining cards — that's how these "best odds" are calculated.
Let Pi be the success probability at stage i, assuming optimal play. Here is the clean derivation.
For rank r, pick the larger of "below r" or "above r" cards (4 each). Rank is uniform over 1–13.
3 Stage 3 — Higher / Lower / Between?
best gap = max(min(r1,r2)−1, |r1−r2|−1, 13−max(r1,r2))
P3 = 4⋅824120⋅50
= 206/375
120 valid rank-pairs after a correct stage 2; their best-gap values sum to 824.
4 Stage 4 — Pick a Suit
P4 = 1349 ≈ 26.5%
After 3 draws, at least one suit is untouched → that suit still has all 13 cards, so always guess it.
5 Stage 5 — Exact Card
P5 = 148 ≈ 2.08%
One specific card out of 48 remaining.
Final Product
P(win) =
12 ×
160221 ×
206375 ×
1349 ×
148
= 206187,425
≈ 0.1099%
≈ 1 in 909.83
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🛡️
Provably Fair
Every game uses cryptographic seeds to ensure results are random and untamperable.
You can verify any game in your history was fair — no trust required.
Seeds & Nonces — View your current seeds and rotate them at any time from inside the verifier.