Fairness and transparency
Randomness Audit
A completed spin should be more than a result on a screen. For recorded spins, Spin the Wheel publishes the information needed to independently check that the revealed seed, the original entry order, and the displayed winner agree.
This page explains the checks available after a recorded spin. It is an audit trail for a specific result, not a promise that a preferred entry will be selected.
- Seed
- 128-bit value
- Commitment
- SHA-256 hash
- Replay
- Runs in browser
The audit trail
How a recorded spin is checked
Each check is concrete. Use the result card and the verifier to compare the recorded values rather than relying on an assertion of fairness.
1. Commit before the reveal
A recorded spin starts with a 128-bit seed and its SHA-256 commitment hash. The commitment is created before the seed is shown in the result card.
2. Reveal the inputs
After the spin completes, the result card reveals the seed. The selected entry depends on that seed, the entry order, and any positive entry weights that were active for the spin.
3. Reproduce the selection
Paste the revealed seed and the same entries into the Spin Verifier. It calculates the same weighted selection rule and shows the entry that the seed produces.
4. Check the commitment
If you also paste the published commitment hash, the verifier computes SHA-256 of the revealed seed and reports whether the two values match.
Independent replay
What to compare
- The revealed seed matches the published SHA-256 commitment hash.
- The submitted entries match the original labels, order, and positive weights.
- The verifier reproduces the same selected entry shown in the result card.
Expected behavior
Why an entry can win again
A repeat is not automatically evidence of a problem. Independent random selections can return the same entry more than once, just as a fair coin can land on the same side repeatedly. If an activity requires unique winners, remove a winner from the wheel before the next spin instead of changing the random selection rule.
Scope of this audit
What this check cannot decide
This audit checks the integrity of a recorded result after the fact. It cannot prove that an entry list was appropriate for a particular event, that participants agreed to the list, or that a custom wheel was not edited before a later spin. Keep the entry list visible to participants when those questions matter.
Selection specification
The reproducible selection rule
The verifier applies this same rule to the submitted entries. Exact labels, order, and positive weights are part of the input, so changing any of them can change the replayed entry.
Questions and answers
Randomness audit FAQ
What does the SHA-256 commitment prove?
It lets anyone compare the revealed seed to the hash recorded before the reveal. A match confirms that the published seed corresponds to that commitment.
Can I verify a weighted wheel?
Yes. Enter each weighted line as weight, entry in the original order. The verifier uses the same positive-weight selection rule as the wheel.
Why does the verifier need the original order?
The selection algorithm walks through the entries in order. Reordering entries changes which entry corresponds to a given seed, even when the labels are the same.
Can I verify a spin without a recorded seed?
No. The independent replay requires the revealed seed and the original entries. A result without those inputs cannot be reproduced by the verifier.
Why can a fair wheel select the same entry again?
Independent random selections can repeat an active entry. If an activity requires unique winners, remove the selected entry before the next spin instead of changing the result after it appears.
Does a matching commitment prove the entry list was eligible?
No. It checks that the revealed seed matches the prior commitment and reproduces the recorded selection rule. Organizers still need to publish and review eligibility rules and the active entry list.