Don't take our word for it. Check the draw.

When a competition closes, we gather every ticket whose entry answered the skill question correctly. Paid and free postal entries sit in this pool on identical terms: one ticket is one slot, with the same odds. Refunded, cancelled and demo entries are removed so they can never win.

Our server then creates a fresh random number for the draw, after entries have closed and at the moment the draw runs. That number, and only that number, picks the winning ticket, and it does it in a way that gives every ticket exactly the same chance. Because the number decides everything, the result is locked in: the same number always picks the same winner, and change one character of it and a completely different ticket wins. Each competition is drawn once, and the number is recorded in the same step as the result.

Publishing the number gives nothing away, because the draw has already happened. It simply lets you check our working. The number, every ticket that was in the draw and the winning ticket are shown here and on each competition's audit page. The checker above does exactly the same sums on your own device, and nothing is sent back to us.

Winner privacy: we publish only a first name and the local area they live in, worked out from the first part of their postcode. Winners can switch this off in their account, in which case the draw shows “Anonymous winner”. Surnames, email addresses, full postcodes and our internal operator records are never shown publicly.

Every draw record is public JSON at api.chooseyouraffles.co.uk/draws/{competition}/verify, where the competition is the last part of its web address. No key, no account. The method is short enough to rewrite in any language:

1. Sort the published ticket list from lowest to highest.
2. For a counter of 0, 1, 2 and so on, take HMAC-SHA256 of the counter (4 bytes, big-endian), keyed with the published number read as hex.
3. Read the first 4 bytes of the result as a whole number. If it is at or above the largest multiple of the ticket count that is no more than 2³², try the next counter. This keeps every ticket's chance exactly equal.
4. Otherwise divide by the ticket count. The remainder is the position of the winning ticket in the sorted list, counting the first ticket as 0.