Random Number Generator

// When one random number is not enough

Typing a range into a search box gets you a single number, and for settling an argument that is the whole job. The moment the number has to do real work, the single-number answer runs out. A raffle needs five different winners without collisions. A teacher picking students needs the same list without anyone coming up twice. A tester seeding a database needs a thousand IDs in one go, in a form that can be pasted somewhere.

That is the gap this page fills. Set the range, say how many you want, and turn on No repeats when each value can only be used once. The result comes back as one large number when you asked for one, and as a copyable block when you asked for more, with buttons for both the comma-separated form a spreadsheet wants and the one-per-line form a text file wants. Quick ranges generate exact 12-, 16-, or 18-digit numbers without making you type all the zeroes and nines.

The count goes to 10,000, and No repeats holds across the whole range rather than across a small buffer. Asking for 1,000 unique numbers between 1 and a billion works and returns instantly, which is where most tools either cap you or freeze.

// Where the randomness comes from

Numbers here are generated with the browser's own cryptographic generator, crypto.getRandomValues, rather than Math.random. The practical difference is predictability: Math.random is fast and fine for a shuffle in a game, but its output can be reconstructed by anyone who watches enough of it. A cryptographic generator is built so that watching past output tells you nothing useful about the next value.

The generator also corrects for a bias most implementations carry. Turning a random word into a number from 1 to 10 by taking the remainder looks correct and is not, because the source's possible values rarely divide evenly by the requested range. This page throws away values in that uneven tail and generates again, so every value in your range is genuinely equally likely. Large whole numbers combine multiple 32-bit words before applying the same rejection rule. Unique results use a Fisher-Yates shuffle, which gives every possible combination the same chance.

All of it runs on your device. The numbers themselves are never sent anywhere, so they are yours before anyone else could see them, and the page keeps working with the network off. That is a real difference from services that generate the numbers on their servers and send them to you.

// fair questions

Can the same number come up twice?

By default, yes. Each generated result is independent, exactly like rolling a die repeatedly, so 7 following 7 is normal rather than a fault. If each value can only be used once, such as in a raffle or when picking people from a list, turn on No repeats and the tool generates without replacement instead.

How do I generate multiple random numbers with no repeats?

Set your range, set How many to the count you need, and turn on No repeats. You can generate up to 10,000 numbers at once, including exact whole numbers up to 18 digits. A unique request also cannot ask for more values than the range holds: you cannot get 11 different numbers between 1 and 10, and the page says so rather than quietly handing back 10.

Is this truly random?

It is cryptographically strong, which is the standard that matters for picks and random selections: the output is unpredictable in practice and free of the rounding bias that a naive implementation introduces. It is not hardware randomness harvested from a physical process such as atmospheric noise. That distinction matters for cryptographic key generation, not for choosing a winner.

Is it fair to use for raffles and giveaways?

Yes. The generation is uniform, so every number in the range has the same chance, and unique results use a full shuffle rather than repeated guess-and-retry, so every combination is equally likely. Nothing weights recent numbers or avoids ones already seen unless you ask it to.

Does anything get sent to a server?

Your numbers do not. They are generated in your browser and never leave it, and nothing is stored between visits. The site does count anonymous usage (which tool was opened, never what you typed or generated), and the page itself keeps working offline once it has loaded.

How wide a range can I use?

The lowest and highest whole numbers can each be up to 18 digits, and the quick-range buttons set exact 12-, 16-, or 18-digit bounds for you. Decimals use a finite precision grid, so six decimal places over a very wide range can still exceed the supported grid. Either way the page explains the limit instead of returning a rounded or subtly biased number.