The Randomizer › How it works

How The Randomizer picks a fair winner

A random name picker is only useful if people trust it. Here's exactly how The Randomizer chooses a winner, and why every name on your list has the same chance.

1. The winner is drawn first

When you press Release the bird or Start the race, the winner is picked straight away, before any animation plays. The draw uses crypto.getRandomValues, your browser's cryptographically secure random number generator, the same kind of randomness used to create encryption keys. It can't be predicted or influenced, by you or by us.

2. Every name has exactly the same chance

A simple way to turn a random number into a position on a list can make some positions slightly more likely than others. The Randomizer uses a method called rejection sampling to avoid that. With 7 names each one has exactly a 1 in 7 chance, and with 500 names exactly 1 in 500.

3. The animation just reveals the result

Once the winner is known, the show begins. The bird circles the crowd and drops on the winner's head, or the race plays out with that name crossing the line first. Where someone stands in the crowd, which lane they get, or the order of your list makes no difference to the odds. That's also why Shuffle is purely for fun.

4. Your list stays on your device

Names are kept in your own browser so they're still there next time. They're never uploaded to our server, never stored by us and never shared or sold.

Ways to pick a winner

• Bird poop raffle in four places: a street concert, the Shibuya crossing, the beach or a pool party.
• Name races: horses, greyhounds, birds or turtles.
• Made for giveaways and raffles and classrooms.