How to Make an Online Ladder Lottery | Fair on Any Phone, and Verifiable

Handing out prizes, setting the order of speakers or hosts, assigning seats, splitting into teams — the more it matters that no one decided the outcome by hand, the more an online ladder lottery shines.

It also works even when people are in different places: everyone watches the same screen and joins at once. At an in-person venue, project it on the big screen and the thrill of tracing each line becomes part of the show.

1. Create an event by entering the options (prizes or roles) and their capacities. Leave a name blank and it's numbered automatically.

2. Show participants the QR code that appears. They just scan it and enter a nickname to join — no app to install and no sign-up.

3. When you close voting, the ladder lottery is generated automatically and the results are revealed. On the big screen you can flip them over one at a time to build the excitement.

Kujipo's ladder lottery publishes a hash (a fingerprint) of the random seed behind the result before the deadline, then reveals the seed itself after the deadline. Participants can reproduce the same result from the published seed and confirm for themselves that it matches the hash committed beforehand.

Thanks to this commit-and-reveal method, it's fundamentally impossible for the organizer or host to cherry-pick the result after the fact. Leaving no room for a “was it rigged?” doubt is the biggest difference from a paper ladder.

A paper ladder has its weak points: whoever draws the lines can work out the outcome, tallying takes effort, and it doesn't work remotely.

Online, all the prep is entering the options. No matter how many people join, the tally is instant, and the results appear on everyone's phone and the big screen at the same time. Because you pick where to vote while watching the competition odds, there's more strategy in play than pure luck.