How RFWIN Picks a Winner You Can Check
"The winner was picked at random" is easy to say and hard to show. RFWIN is a winner picker built to show it: every draw gets a public proof page at rfwin.uk/d/<id> with the inputs, the winners and a fresh fairness check, and the maths can be re-run by anyone.
The three inputs
- A committed server seed. RFWIN generates a secret seed and publishes its hash (the commitment) before the draw. The seed is revealed afterwards, and anyone can confirm it matches the commitment.
- Public randomness from drand. drand is a randomness beacon run by the League of Entropy, a group of independent organisations. It publishes a new unpredictable value every few seconds that nobody, including RFWIN, can predict or change.
- A hash of the entry list. Entries are fixed and hashed, so the list cannot be edited after the fact without breaking the proof.
How the winners fall out
RFWIN computes a draw digest as sha256(server_seed | drand_value | entrants_hash). For each prize slot p, it takes sha256(draw_digest | p) modulo the total number of tickets over the entrant pool in entry order. That picks the winner for that slot. Change any input and the winners change, which is why no one could have hand-picked the result.
What the proof page shows
- The draw title and, for stations, the station and show name.
- Date, number of entries and the prizes.
- Winners and ordered backup winners, with names masked for privacy (for example
J••n D••e). Raw names and emails are never stored, only hashes and masked labels. - A verdict from a fresh check:
verified,verified_hash_level,partially_verified,mismatchornot_drawn_yet.
Quick draws vs step-by-step draws
The free picker on the home page runs an instant draw that uses the drand round current at draw time. It is fast and still verifiable. The step-by-step API (paid plans) is stronger: you create the draw, add entrants, then close it to a future drand round, so the randomness did not exist when the entry list was locked.
What it does not prove
RFWIN shows that the published winners follow exactly from the published inputs. It does not prove who was eligible, that every valid entry was included, or that the organiser ran only one draw. Those come down to your contest rules. RFWIN does not by itself make a contest legally compliant.
Free and paid
Free: unlimited draws of up to 10,000 entrants each, public proof pages with RFWIN branding, backup winners and station or show labels. The full masked entrant list stays published for 12 months, then non-winning rows are archived while the winners and hashes are kept, so the proof still verifies at hash level. Paid Rewards Fuel plans remove the branding, lift the entrant cap, add the authenticated API and MCP, and keep entrant lists. Draws can also be public or private (unlisted).
Want the details? Read the technology page, or see how an AI assistant can check a draw for you.