Coin Flip Generators
Flip a virtual coin, once or a thousand times.
Coin Flip is a free online tool that flip a virtual coin, once or a thousand times. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free: no account, no quota, no watermark
- Category
- Generators
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 2
- Works offline
- Yes, after the first visit
About Coin Flip
The result comes from `crypto.getRandomValues`, the browser's cryptographically secure generator, rather than `Math.random`, which is fast but not uniform enough to be trusted for anything where the outcome matters. A real coin, incidentally, is not quite fair either: a 2007 Diaconis, Holmes and Montgomery analysis found a caught flip lands on the same face it started roughly 51% of the time.
How to use it
- Enter number of flips and flip again.
- Results update the moment anything changes.
The 2 settings
| Setting | What it does | Default |
|---|---|---|
| Number of flips | Range 1–10000. | 1 |
| Flip again | On or off. Off by default. | Off |
Under the hood
| Runs on | plain JavaScript: runs the whole thing |
| Controls | Number of flips, Flip again |
Questions
Is this genuinely random?
It draws from the operating system's entropy source through WebCrypto, the same generator used to produce cryptographic keys. For deciding who buys lunch, comfortably more than sufficient.
Why did I get six heads in a row?
That happens once in 64 sequences, so with any real number of flips it is expected. Runs feel unlikely but are entirely normal; expecting them to be rare is the gambler's fallacy.
What are the limits on number of flips?
It accepts 1 to 10000, starting at 1.