Random Number Generator — Free Online Tool

A random number generator (RNG) produces numbers within a specified range for testing, sampling, simulations, or quick utility tasks. SWEDevTools: Prism generates numbers in your browser using the Web Crypto API, with options for min/max, count, decimal precision, and an optional unique mode for non-repeating integers. It’s ideal when you need repeat-free test IDs, dice-roll style values, or bulk numeric fixtures without writing a script.

Features

• Web Crypto randomness: Uses crypto.getRandomValues() instead of Math.random() for stronger randomness characteristics.
• Bulk generation: Generate up to 1000 numbers at once for fixtures, seeds, or sampling.
• Unique integer option: Prevent duplicates when generating integers (with validation to avoid impossible requests).
• Decimal precision control: Choose 0–10 decimal places to generate ints or floats for realistic datasets.

Frequently Asked Questions

Is this RNG cryptographically secure?

It uses the Web Crypto API (crypto.getRandomValues), which is appropriate for many security-sensitive uses. For production secrets, still follow your platform’s best practices and threat model.

Are min/max values inclusive?

Yes. The generator is intended to include both endpoints for integer output. For decimals, values are generated within the range and rounded to the requested precision.

Why does unique mode sometimes error?

If you request more unique integers than the range contains (for example, 10 values from 1–6), the tool returns an error because it’s mathematically impossible.

Can I generate negative numbers?

Yes. Set a negative minimum value (for example, -10 to 10) for test data and simulations.

Does unique mode work with decimals?

Unique is most reliable for integers. With decimals, rounding can create collisions more easily; consider increasing precision or leaving unique disabled.

How do I generate a dice roll?

Set min=1, max=6, decimals=0, count=1. Increase count for multiple rolls.

Can I use this for load-testing IDs?

Yes for quick fixtures. For large-scale workloads, consider a deterministic generator or your DB’s sequence/UUID functions depending on requirements.

Do you store or send generated numbers anywhere?

No. Generation runs locally in your browser.

What happened to smalldev.tools?

smalldev.tools is no longer available. Prism by SWEDevTools offers the same developer tools and more, with offline support, pipeline chaining, and completely free usage — no signup required.