sprytools

Random Number Generator

Generate random numbers instantly: integers, decimals, unique sets (1–1000), RPG dice (d6/d10/d20/d100), coin flips, and random picks from a custom list. Seeded reproducibility included. Free, 100% client-side.

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Random Number Generator

Our free random number generator produces truly unpredictable results for any purpose — from simple number picks and lottery draws to RPG dice rolls, coin flips, and random selections from a custom list. All calculations run entirely in your browser using the Web Crypto API (crypto.getRandomValues()); nothing is sent to any server.

What you can generate

Integers — Enter a minimum and maximum value and click Generate. Get a single number or a batch of up to 1,000 numbers at once. Enable “No duplicates” for a guaranteed unique set, perfect for lottery simulations or prize draws.

Decimals — Switch to Decimal mode to get floating-point numbers with 1–10 decimal places. Useful for scientific simulations, statistics, or generating random probabilities.

Dice rolls — The Dice tab supports all common RPG die types: d6, d10, d20, and d100. Roll up to 20 dice at once and see individual results plus the total. Enter a custom die size for non-standard dice.

Coin flip — Flip a virtual coin and track your streak. The tool records the last 10 flips and shows a running heads/tails count so you can spot (or debunk) lucky streaks.

Random list picker — Paste a comma-separated list of options and let the tool pick one or more for you. Great for picking a random restaurant, assigning tasks, or running giveaways.

Reproducibility with seeds

Enter an optional seed number to switch from cryptographic randomness to a deterministic sequence. The same seed always produces the same output — useful for games that need fair, auditable randomness, A/B test reproducibility, or sharing a specific draw with someone else.

How is this random?

By default, the tool uses crypto.getRandomValues(), the same entropy source browsers use for TLS key generation. It is statistically indistinguishable from true randomness. When a seed is provided, the tool uses the mulberry32 PRNG algorithm — fast, high-quality, and fully deterministic for a given seed.

Frequently Asked Questions

How do I generate lottery numbers? Set Min to 1, Max to 49 (or your lottery’s maximum), set Count to 6, enable “No duplicates”, and click Generate. Each click produces a fresh draw.

Can I generate numbers with a specific distribution? The tool produces uniformly distributed random numbers — each value in the range has an equal probability of being selected. Gaussian or custom distributions are not currently supported.

What is the maximum count I can generate? You can generate up to 1,000 numbers in a single click. For unique numbers, the count cannot exceed the size of your range.

How does the dice roller work? Each die is rolled independently using a separate random draw. A d6 returns 1–6, a d20 returns 1–20, etc. The total is the sum of all individual dice.

Is this safe for security-sensitive use? The default (unseeded) mode uses crypto.getRandomValues(), which is suitable for generating tokens, nonces, and other security-sensitive values. The seeded mode is deterministic and should not be used for security purposes.

FAQ

How do I generate a random number between two values?

Enter your minimum and maximum values in the "Numbers" tab and click Generate. The tool instantly returns a cryptographically random integer (or decimal) within your specified range.

How does the unique numbers feature work?

Enable "No duplicates" to get a set of unique numbers. The tool uses a Fisher-Yates shuffle internally, so each number in the range appears at most once. For example, generating 6 unique numbers from 1–49 simulates a lottery draw.

How do I roll RPG dice?

Switch to the "Dice" tab. Choose a preset (d6, d10, d20, d100) and set how many dice to roll, or enter custom die sides. The tool shows individual rolls and the total sum.

Can I reproduce the same random sequence?

Yes. Enter a seed number in the seed field before generating. The same seed always produces the same sequence — useful for games, testing, or sharing results with others.

Is this truly random?

By default the tool uses your browser's crypto.getRandomValues() API, which provides cryptographically secure randomness. When a seed is entered, it switches to a deterministic PRNG (mulberry32 algorithm) to enable reproducibility.