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Coin Flip — Heads or Tails

Heads or tails — a cryptographically fair 50/50 flip.

Call it in the air - heads or tails? The flip is cryptographically 50/50.

About the Coin Flip

Who kicks off, who presents first, who gets the last slice — some decisions are best left to chance, as long as the chance is honest. Most coin-flip apps quietly use Math.random(), which is fine for animations but not designed for fairness. This flip draws a single bit from your browser’s cryptographic RNG, the same source security software trusts, giving heads and tails an exactly equal probability on every toss.

The running tally keeps score across flips, so you can watch the percentages converge toward 50/50 the longer you flip — a surprisingly satisfying demonstration of the law of large numbers.

How to use it

  1. 1Call heads or tails, then click Flip the coin.
  2. 2Read the result — click Flip again for another independent toss.
  3. 3Watch the running tally, or Reset to start the count over.

Frequently asked questions

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