Coin flip
Heads or tails, using the browser's cryptographic random generator.
- Runs in your browser — nothing you enter is uploaded
- No sign-up, no quotas, free to use as often as you like
How it works
Nobody has a coin any more. This one uses the browser's cryptographic random number generator rather than the ordinary pseudo-random function most pages use — which matters if you are settling something that matters, and is interesting if you are not.
Why the randomness source matters
The usual JavaScript random function is a deterministic algorithm seeded from a starting value; it is fine for animations and unacceptable for anything anyone might want to predict or dispute. This uses the cryptographic generator instead, the same source used to create encryption keys, which draws on genuine system entropy.
Flipping many at once
Set the number of flips and you get the counts, the percentages and the longest streak. That last figure is the interesting one: in a hundred flips a run of six or seven identical results is entirely ordinary, although it feels rigged. Long streaks are what real randomness looks like, and their absence is what fake randomness looks like.
Fair by construction
A single random byte is read per flip and its lowest bit taken, which splits the possible values exactly in half. There is no bias in either direction.
Coin flip — questions
Is it actually random?
It uses the browser's cryptographically secure random generator, seeded from system entropy — far stronger than the ordinary pseudo-random function.
Can I flip more than one coin?
Yes, up to ten thousand at once, with counts, percentages and the longest streak.
Why did I get seven heads in a row?
Because that is normal. Streaks of six or seven in a hundred flips are ordinary, and their absence would be the suspicious result.
Is the coin weighted?
No. Each flip reads a random byte and takes its lowest bit, which divides the outcomes exactly evenly.
Does it work offline?
Yes, once the page has loaded.