How we calculate

The tools here do not calculate anything about you; they pick at random. So the method that matters is where the randomness comes from and how a random value is turned into a pick. The full description is on How our randomness works; this is the short version.

The source

Every tool takes its random values from crypto.getRandomValues(), the Web Crypto generator built into your browser. It is a cryptographically secure pseudo-random generator seeded by your operating system. No tool on this site calls Math.random().

Whole numbers without bias

To pick one of n options a tool draws a 32-bit value and throws it away if it falls in the uneven remainder at the top of the range, then draws again. Every option gets exactly the same chance.

Shuffles

Lists are shuffled with the Fisher–Yates method, using one unbiased draw per position. Each possible order is equally likely.

Built-in lists

Name, word and place generators pick from lists written into the page. A list is a selection, not a complete record, and a pick says nothing about how common something is in the real world.

Placeholder data

Phone numbers use 555-0100 to 555-0199, the range the North American Numbering Plan Administrator keeps for fictitious use. Email addresses use the reserved domains example.com, example.org, example.net and the .test ending. No tool generates government ID, payment card, bank or device numbers.

Where the calculation happens

In your browser. The page downloads the tool once and does the work on your device, so results appear as you type and your inputs are not sent to us.

What a tool page shows

The date the page was last updated.
How the result is produced.
On the tools rebuilt on our current template: the formula or rule, a worked example you can check by hand, and the sources the numbers come from, linked. Older tools are being brought up to that standard.

Sources we rely on

Limits

RandomVal is for games, classrooms, creative work and software testing. A result is a random pick and nothing more: do not use it for anything that needs an audited or legally certified draw, and never present generated placeholder data as a real person's details.