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Random Number Generator

Instant, secure, and completely offline, your numbers never leave your device.

How Random Number Generator works

The Random Number Generator produces one or thousands of random integers within any range you define, from a single lottery pick to a full list of unique identifiers. Each number is drawn from the Web Crypto API (crypto.getRandomValues), which is backed by the cryptographically secure entropy source built into your operating system. This is fundamentally different from Math.random(), which uses a deterministic pseudo-random algorithm that can be predicted if the seed is known.

The tool also offers a no-duplicates mode for draws where each value must appear at most once (implemented with rejection sampling), optional ascending or descending sorting, and one-click copy for the generated list. All generation logic runs locally in your browser; nothing is sent to any server.

Written by Bastien Sulyan

How to use Random Number Generator, step by step

  1. Enter the minimum and maximum values of the range (integers, including negative values).
  2. Enter how many numbers you want to generate.
  3. Toggle "No duplicates" on if each number should appear at most once in the output.
  4. Click Generate.
  5. Copy the result with the one-click copy button, or sort it ascending or descending before copying.

Common use cases

  • Drawing six unique lottery numbers between 1 and 49 using the no-duplicates mode.
  • Randomly selecting 10 winners from a list of 500 participants numbered 1 to 500.
  • Generating a list of 100 random student IDs in a range for a class simulation exercise.
  • Picking a random number between 1 and 6 to decide whose turn it is at a board game when no physical dice are available.

Frequently asked questions

Does this tool send my numbers or inputs to a server?

No. Everything runs in your browser using JavaScript and the Web Crypto API. No network request is made during generation and the tool works offline once the page has loaded.

How random are the numbers really?

crypto.getRandomValues is seeded by the operating system kernel using hardware entropy sources (thermal noise, interrupt timing and similar). It is the same source used by cryptographic key generation. Math.random(), by contrast, uses a software PRNG that is fast but deterministic and predictable if its state is known. For most applications such as raffles and sampling the difference is academic, but using the secure source costs nothing and is the right default.

How does the no-duplicates mode work?

The tool draws numbers one at a time. If a drawn number has already been selected, it discards it and draws again (rejection sampling). The range must contain at least as many distinct integers as the count requested; the tool validates this and shows an error if the request is impossible. For large counts relative to the range size, this approach can take many attempts; the tool caps retries to prevent infinite loops.

Can I generate numbers outside the integer range?

The tool generates integers (whole numbers), including negative integers. Decimal numbers are not supported directly. To simulate rolling a six-sided die, set the range to 1 to 6. To pick a random percentage, set 0 to 100.

Is the generator suitable for security or gambling purposes?

The underlying source (crypto.getRandomValues) is suitable for cryptographic use, but this tool is a convenience utility, not a certified gambling or security-grade system. For regulated gambling or cryptographic key generation, use a dedicated certified platform.

Can I use it for lottery numbers or a raffle?

Yes. Set the range to match your lottery (for example 1 to 49), enter the count (for example 6), enable no-duplicates, and click Generate. The secure source makes the draw statistically fair and unbiased. You can re-generate as many times as you need.

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