Random Number Generator — Dice, Coin Flip & UUID

Pseudo-random (Math.random) uses a deterministic algorithm seeded from time — fast, but predictable if you know the seed. Cryptographic random (crypto.getRandomValues) is sourced from operating-system entropy and is unpredictable even to the user. We use the crypto API throughout, so dice rolls, coin flips and number picks are genuinely unpredictable.

Yes — and provably so. We use rejection sampling on top of crypto.getRandomValues to avoid the modulo bias that affects naïve `random % range` code. Every value in the chosen range has exactly equal probability. The same approach is used in security-grade lottery systems.

For tabletop RPGs, board games and casual fun: absolutely yes. The randomness is stronger than physical dice (which have manufacturing imperfections). For high-stakes uses (gambling, audited drawings) you should use a regulated provider — we don't certify or audit.

Crypto random is only marginally slower than Math.random in modern browsers, and it's the right default. Math.random has known bias and predictability quirks; for any tool that affects outcomes (even casual ones), crypto is the cleaner choice. There's no downside.

We use crypto.randomUUID() when available (all modern browsers since 2022), which produces a v4 UUID — 122 random bits with 6 fixed bits identifying the version. The probability of collision across the lifetime of the universe is negligible.

Drawing winners from a giveaway list, picking a restaurant from your shortlist, choosing who buys lunch, randomising interview order — anywhere you have a finite list of options and want one (or all of them, shuffled). Just paste one item per line.

Nothing. Every roll, flip and pick happens locally in your browser. We don't log inputs, outputs, or that you visited the page (beyond standard server access logs).