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Coin Flip

A real online coin flip, generated from genuine physical entropy — not a fake animation.

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How this coin flip works

Most online coin flippers just call Math.random() in your browser. This one is different: every flip calls a live API that pulls entropy from a real physical process (by default, nanosecond-scale timing noise from the server's own CPU), mixes it cryptographically, and maps it to heads or tails using rejection sampling — a technique that guarantees neither side is even slightly more likely than the other. If you want to see exactly how a given flip was generated, or pick a different entropy source such as live earthquake data or quantum vacuum noise, try the full random number generator.

Frequently asked questions

Is this coin flip actually random?

Yes. Each flip is generated from real physical entropy, mixed with a cryptographic hash, giving heads and tails exactly equal probability.

What are the odds of heads vs tails?

Exactly 50/50. The rejection-sampling method used guarantees neither side is favored, unlike naive modulo-based methods which can introduce tiny biases.

Can I see proof of how the result was generated?

Yes — the full random number generator shows a complete technical breakdown of the raw entropy, the mixing step, and the exact mapping calculation for every result.