Tool
Rock Paper Scissors
Play a fair round against a true-random opponent.
Rock Paper Scissors
Play a round against the computer: pick rock, paper, or scissors, and it picks its own move at the same moment, with a genuinely random 1-in-3 chance for each option.
No hidden logic tries to counter your choice -- the computer's move is locked in by randomness before it even knows what you picked.
It's a single round at a time, so you can play once to settle something quickly or play several rounds back to back for a best-of series.
How the Rock Paper Scissors works — and why it's fair
The computer's move is drawn from a random number generator over exactly 3 outcomes, using crypto.getRandomValues with rejection sampling to make sure all three options (rock, paper, scissors) get a perfectly even one-third share -- a naive approach using a raw byte modulo 3 would very slightly favor the first outcome, since 256 doesn't divide evenly by 3, so rejection sampling discards the rare byte values that would cause that bias.
Crucially, the computer's move is generated independently of your input and before your click is read for comparison purposes -- it isn't peeking at your choice and then picking a winning counter-move. The comparison logic only kicks in after both moves already exist.
This is the same rejection-sampling family of fix used by the dice roller and letter generator, just applied to a much smaller set of outcomes -- 3 options instead of 20 die faces or 26 letters, but the underlying math problem (an outcome count that doesn't evenly divide 256) is identical.
The game itself has centuries of history under various names across different cultures before settling into the rock-paper-scissors form most people know today -- but the fairness question for a digital version is a modern one, since a scripted or predictable computer opponent could quietly be built to win more often than chance, which is exactly what the independent 1-in-3 draw here rules out.
When people reach for rock-paper-scissors
It settles small disputes fast -- who does the dishes, who gets the last slice, who goes first in a board game -- the same way it would in person, but without a debate over whether someone threw late or reacted to the other player's hand.
It also works as a genuine tiebreaker layered on top of another tool's result here (say, two people tie for a raffle prize), and as a quick practice opponent for kids learning the game before they play it against a person.
Some people use it as a lightweight probability demonstration in a classroom setting, running a batch of rounds and tallying how close the win/loss/tie split lands to the expected even distribution.
Some workplaces use a quick round against this tool as a genuinely neutral way to decide who takes an unpopular task, precisely because there's no human opponent to suspect of reading tells or reacting late.
Frequently asked questions
Does the computer see my move before choosing its own?
No -- its move is generated independently and isn't adjusted based on your pick.
Are all three outcomes exactly equally likely?
Yes, each is drawn with an even 1-in-3 chance using rejection sampling to remove any modulo bias.
Can I play best-of-3 or best-of-5?
You can play repeated single rounds back to back and tally the results yourself; each round is an independent fresh draw.
Is there a lizard-spock or other expanded variant?
This tool sticks to the classic 3-option version.
Can this settle a dispute between more than two people?
It's built for one person versus the computer; for group decisions among several people, the name picker or spinner wheel are better suited.
Can I see a running record of wins, losses, and ties?
The tool shows each round's result as it happens rather than keeping a persistent scoreboard across sessions.
Is there any pattern to how the computer picks over many rounds?
No -- each round is an independent draw, so there's no learnable pattern across rounds regardless of how many times you play.
Can I play against a friend using this tool instead of the computer?
It's built for one person versus the computer; for two human players, an in-person hand game or a two-input version would be needed, which isn't what this tool provides.
Does the computer ever throw the same move several times in a row?
Yes -- each round is an independent 1-in-3 draw, so streaks of the same move happen by chance just as they would with a fair human opponent.