How the picking works

A name picker is only useful if people trust it. Here is exactly what happens when you press the button, in plain words.

1. The winner is chosen before anything moves

The moment you press Pick a name, the winner is decided. Only then does the wheel spin, the ducks race, the hat shake or the claw move. The animation is a show that plays out a result that already exists. That means:

• a hard or soft "spin" can't change the outcome;
• every game is exactly as fair as every other game;
• the claw never "slips", and a duck that leads early has no advantage.

2. Secure randomness from your browser

The choice uses crypto.getRandomValues, the random number generator built into every modern browser for security work such as creating passwords and encryption keys. It is far less predictable than the everyday random function many websites use.

Turning a random number into "one of your names" is done without bias. The simple shortcut of taking the remainder of a big random number skews the odds slightly towards the first names in a list; we throw away the few random numbers that would cause that skew and draw again, so every name truly has the same chance.

3. Extra chances are real chances

If you write Anna *3, Anna is treated as three entries, exactly like putting her name in a hat three times. On the wheel her slice is three times as wide, so the picture always matches the odds.

4. Several winners, no duplicates

When you ask for several winners, names are drawn one after another without putting them back, so nobody can win twice in the same draw. With No repeats until everyone is picked, the picker remembers who has already had a turn (on your device only) and leaves them out until everyone has been picked, then starts a new round.

5. Your names stay on your device

• The list is processed entirely in your browser. Nothing you type is sent to our server.
• Your browser keeps a few things on your device so they are there next time: your last list, your edits on each ready-made list page, saved lists, settings (including the team, pair and list randomizer options), the no-repeats round, "Absent today" marks on the classroom page, your theme and cookie choice, and an offline copy of the site's pages (a service worker cache) so the picker works without a connection.
• Photos you add to names are shrunk to small squares and kept only in this browser. They are never uploaded and never put in share links.
• You can remove all of it at any time by clearing your browser's site data.
• Share links carry the list after the # in the address. Browsers never send that part to a server, but anyone you give the link to can see the names, so share it only with people who should.

6. What we can't promise

Random means random, and true chance has streaks: a coin can land on heads four times running. That's why the picker starts with No repeats until everyone is picked: everyone gets a turn before anyone is picked again, a new round never starts with the name that won last, and the progress is remembered on your device, so it carries on when you come back. With 50 names, that's 50 different winners before any name can repeat.

The exceptions are the pure-chance lists: coin flips, dice, yes or no, left or right, rock paper scissors and the number wheels. There, every spin is independent, as it would be with a real coin or die. You can choose any of the three anywhere under Settings → After each pick: Keep the name for pure chance, No repeats, or Remove the winner.

Questions or ideas? Get in touch.