Amidakuji Generator (Ghost Leg Lottery) | Free Online Tool
Enter participant names and outcomes (prizes, roles, tasks), and instantly generate a random amidakuji (Japanese "ghost leg" ladder lottery) that guarantees a fair one-to-one match for every participant. Great for picking who does what, party games, or drawing lots. Everything runs in your browser — nothing you type is sent anywhere.
Everything you enter is processed entirely in your browser and is never sent anywhere.
Results
Press "Generate ladder" to see the results here.
Click a name to trace its path through the ladder.
How to use
- Enter one participant name per line.
- Enter the same number of outcomes (prizes, roles, tasks), one per line.
- Press "Generate ladder" to create a random amidakuji and reveal each pairing.
How it works
What is amidakuji?
Amidakuji (阿彌陀くじ, also called "ghost leg" lottery) is a traditional Japanese method for assigning outcomes fairly and at random. It draws one vertical line per participant, connected by horizontal "rungs" placed at random heights. Each participant traces their own line from top to bottom, switching to the neighboring line whenever they cross a rung, until they reach an outcome at the bottom.
Why the result is always a true one-to-one match
Rungs are placed under one rule: within the same row, two adjacent positions can never both hold a rung. Under that rule, every row is just a set of swaps between neighboring lines, and any set of non-overlapping swaps is itself a permutation (a rearrangement where nothing is duplicated or dropped). Composing permutations row by row from top to bottom always produces another permutation, no matter how the rungs happen to fall. In practice this means the final pairing between participants and outcomes is always a genuine one-to-one match — no two participants can ever land on the same outcome, and no outcome is ever left unclaimed.
How the number of rows is chosen
The number of rows (rungs) is chosen automatically based on the number of participants: fewer participants means fewer rows, more participants means more rows, within a range of 10 to 60 rows. A taller ladder looks more complex, but it never changes the one-to-one guarantee above.
About the randomness source
Rung placement uses the Web Crypto API's crypto.getRandomValues(), a cryptographically secure random number generator. Math.random() is not used, since it can be predictable in some environments and this tool is meant for fair, unbiased draws.
FAQ
Is anything I type sent to a server?
No. Generating the ladder and computing the pairings happens entirely in your browser — nothing is sent over the network.
Can two participants end up with the same outcome?
No. Because of how amidakuji ladders are structured, the result is always a strict one-to-one match. Two people landing on the same outcome, or an outcome being left unclaimed, cannot happen.
What is amidakuji / a "ghost leg" lottery?
It's a traditional Japanese way to randomly and fairly assign people to outcomes, commonly used to decide who hosts a party, who does a chore, or who wins a small prize. The name "ghost leg" comes from the ladder's shape, which resembles a set of legs.
How many participants can I enter?
Between 2 and 20 participants (and the same number of outcomes).
What happens if I generate again with the same names?
Each click of "Generate ladder" uses fresh randomness to build a new ladder, so the pairings change every time. There's no way to save or lock in a specific result.
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