Random number generator - numbers, list picker, dice and coin flip

The generator uses crypto.getRandomValues - the browser’s cryptographically secure source of randomness - instead of the predictable Math.random(). To avoid modulo bias (where some numbers come up slightly more often because the range does not divide the generator’s pool evenly), it applies rejection sampling: values from the uneven tail of the pool are discarded and drawn again. As a result every number in the range has exactly the same chance.

For unique numbers the tool draws without replacement, and lists are shuffled with the Fisher-Yates algorithm, which gives every possible order the same probability. Nothing is sent to a server, so lists of names stay on your device.

• A random number from 1 to 100 (or any range, including negative and decimal numbers) for games, quizzes and tests.
• Numbers without repeats - for raffle tickets or lottery-style picks such as 5 of 69 (it is just a draw and does not improve your odds of winning).
• Picking from a list - a giveaway winner, who answers next, the order of presentations.
• Splitting into teams - sports teams in PE class, project groups, tournament brackets. Team sizes differ by at most one person.
• Dice and coin - d4, d6, d8, d10, d12, d20 and d100 for board games and tabletop RPGs, plus heads or tails for quick decisions.

In a fair draw the chance of one specific result is 1 / number of possible outcomes. When drawing without repeats you count combinations: choosing 6 from 49 gives 49! / (6! · 43!) = 13,983,816 possible sets.

Previous results do not affect the next ones: after five tails in a row the chance of heads is still 50% (the gambler’s fallacy). For giveaways, publish the rules before the draw, record your screen or take a screenshot of the result, and make sure each participant appears on the list only once unless the rules allow extra entries - the “Remove duplicates” option helps with that.