Most “random number” tools quietly use Math.random(), fast, but never built to be unpredictable. This one doesn’t.
Free data tool
Random Number Generator
One or many random numbers in any range, using your browser's cryptographic random source, the same one used for encryption keys.
Runs entirely in your browser. Nothing is sent anywhere, and nothing is ever reused or logged.
Why this doesn't use Math.random()
JavaScript's built-in Math.random() is fast but was never designed to be unpredictable, its internal state can, in principle, be inferred from enough output. This generator uses window.crypto.getRandomValues instead, the same cryptographically secure source your browser uses to generate encryption keys, with rejection sampling to make sure every number in your range is exactly equally likely, not just approximately.
Random number generator FAQ
Is this actually random, or just Math.random()?
It uses window.crypto.getRandomValues, the browser's cryptographically secure random source, the same one used for generating encryption keys, not Math.random(), which is faster but not designed to be unpredictable. Numbers are drawn with rejection sampling to avoid the small bias a naive modulo operation would introduce at the edges of your range.
What happens if I ask for more unique numbers than the range allows?
It tells you rather than guessing. If you ask for 10 unique numbers between 1 and 5, there are only 5 possible values, so no valid answer exists, the calculator shows an error explaining exactly why instead of silently returning duplicates or an incomplete list.
Can I generate decimal numbers, not just integers?
Yes, switch to decimal mode and choose how many decimal places you want. Integer mode and decimal mode use slightly different generation logic under the hood, integers are drawn directly from the allowed range, decimals are generated then rounded, so switching modes can change results even for the same min and max.
Can I get the same sequence of numbers again later?
No, and that's intentional. This generator has no seed value you can set or reuse, every run draws fresh from the cryptographic random source, so results are never reproducible. If you need a reproducible sequence for testing, you want a seeded pseudo-random generator instead, a different tool for a different job.
Is my data private?
Yes. Every number is generated entirely in your browser. Nothing is sent to a server.
Free random number generator by ANUPRESS
Why this uses your browser’s cryptographic random source
JavaScript’s built-in Math.random() is fast and fine for a game animation, but its internal state was never designed to resist being inferred from enough output. This generator uses window.crypto.getRandomValues instead, the exact source your browser already relies on to generate encryption keys, with rejection sampling on top so every number in your chosen range is exactly, not approximately, equally likely.
Unique numbers are a different problem than independent ones
Drawing five independent random numbers and drawing five unique ones aren’t the same task under the hood, and asking for more unique numbers than a range actually contains has no valid answer at all. Rather than silently returning duplicates or a short list, this generator checks first and tells you plainly when the numbers don’t add up.
No seed means no repeats, on purpose
This generator can’t be asked to reproduce a previous sequence, there’s no seed value stored or exposed anywhere. Every run draws fresh from the cryptographic source. If a project genuinely needs a reproducible sequence, that’s a seeded pseudo-random generator, a deliberately different tool built for a deliberately different job than the one this one is built for.