Random Number Generator

What is Random Number Generator?

Random Number Generator produces integers or floating-point numbers within specified ranges using the Web Crypto API's cryptographically secure random number generator (CSPRNG). It supports uniform distribution, normal (Gaussian) distribution with configurable mean and standard deviation, and custom discrete probability distributions. The tool can generate single values, sorted lists, or unique (non-repeating) sets, and exports results in various formats.

Statisticians generating random samples, developers creating test data, and researchers performing randomized experiments. The tool runs entirely in your browser — your data never leaves your device.

How to Use Random Number Generator

1. Set the minimum and maximum values for your desired range
2. Choose integer or decimal output and the number of values to generate
3. Select the distribution type — uniform, normal, or custom weighted
4. Generate and copy the results, sorted or in generation order

Common Use Cases

• Generating lottery-style number picks with guaranteed uniqueness within a range
• Creating random test inputs for software testing with specified distributions
• Producing random assignment numbers for A/B test participant allocation
• Generating dice rolls, coin flips, or other probability simulation inputs

Pro Tips

• Web Crypto CSPRNG is suitable for security-sensitive randomness (tokens, nonces) unlike Math.random() which is predictable — for non-security uses, both produce statistically uniform distributions
• For unique random numbers, the tool uses rejection sampling when the set size is small relative to the range, and Fisher-Yates shuffle on the full range when the set is large — both guarantee uniform selection
• Normal distribution generation uses the Box-Muller transform — values technically range from negative to positive infinity, so apply range clipping if you need bounded normal-like values

Why Use This Tool?

• Privacy-first: All processing happens locally in your browser. No data is transmitted to any server.
• No installation required: Works in any modern browser on desktop or mobile.
• Completely free: No account, no credit card, no usage caps.
• Fast and reliable: Powered by modern Web APIs for near-instant results.

Related Concepts

Learn more about related topics: CSPRNG, Uniform distribution, Normal distribution, Random sampling.

Frequently Asked Questions