Proof
Giveaways your viewers can check.
Anyone can say they picked a winner fairly. Proof lets the viewers check. Perchy commits to the draw before entries open, reveals how it was made afterwards, and anyone can re-run it in their own browser and get the same winner.
Try it
Run a real draw, then try to cheat.
This is the same code the app uses, running in your browser with twelve sample entrants. Nothing is sent anywhere.
- 1
Commit
Before entries open, Perchy picks a secret seed and publishes only its fingerprint.
- 2
Close the entries
The entry list is fingerprinted too, so nobody can add or remove a name afterwards.
- 3
Draw
The seed and the entry list decide the winner by a fixed recipe. No hand involved.
- 4
Verify
Anyone can recompute everything from the public numbers. Six checks, all in your browser.
12 sample entrants
- mira_px2
- فيصل
- Sam K
- leo_v
- Norax2
- kenji
- Dalal
- tariq_77
- Beax2
- yousef
- Ana
- Hamad
Subscribers get two tickets in this sample, as the weighting rules allow. Only hashed ids are published, never names.
What the public sees
- Commitment
- Not published yet
- Entry list fingerprint
- Not published yet
- Seed
- Not published yet
- Winner
- Not published yet
Verification
Draw a winner, then press verify. The checks appear here.
How it works
Commit, close, draw, verify.
Four steps, in this order, and the order is the whole point.
- 1
Commit
Before entries open, Perchy picks a secret seed and publishes its fingerprint. A fingerprint cannot be turned back into the seed, but it can be checked against it later.
- 2
Close the entries
When entries close, the full list gets a fingerprint too. Add a name, remove one or change a weight and the fingerprint no longer matches.
- 3
Draw
The seed and the list's fingerprint go through a fixed recipe that picks a ticket. Subscribers can hold more than one ticket, if you set it up that way.
- 4
Verify
The seed is revealed. The public page shows the commitment, the list and the result, and a button that re-runs everything in the visitor's own browser.
The recipe is a standard keyed hash (HMAC with SHA-256) over the seed and the list's fingerprint, reduced to a ticket number with no bias toward small numbers. Once the commitment is public, nobody, including us, can steer the result without the checks failing.
Honestly
What Proof proves, and what it does not.
We would rather you trust this for the right reasons.
It proves
- The winner came from the committed seed and the published entry list
- The list was not changed after entries closed
- Anyone can check it without trusting you or Perchy
It does not prove
- That every entrant was a real, separate person
- That your entry rules were fair or were followed
- That the prize was sent
Giveaway rules differ by country and by platform. Offer a free way to enter, publish your rules, and read what your platform and your local law require. Proof checks the draw, not the legality.
Free
On every plan, because it is the feature people talk about.
The plans differ only in how many giveaways can be open at once.
3
giveaways open at once
Proof included
15
giveaways open at once
Proof included
60
giveaways open at once
Proof included
Questions