Random Number Generator
Generate random integers in a custom min/max range. Choose Math.random or this browser's crypto.getRandomValues CSPRNG, with optional unique results.
Random Number Generator
Pick integers in a range. Math.random is not cryptographic; crypto.getRandomValues uses this browser's CSPRNG.
Only values min, min+step, min+2·step, … up to max. Example: min 1, max 10, step 2 → 1, 3, 5, 7, 9.
Neither option is a hardware entropy source. Use crypto.getRandomValues when you need unbiased draws from this browser's CSPRNG.
What is a random number generator?
A random number generator produces integers in a range you set. This page defaults to Math.random and optionally uses crypto.getRandomValues() (browser CSPRNG). It does not store draws or run a lottery.
How to Use the Random Number Generator
Set your range. Enter a minimum and maximum value. The default is 1–100, but negative numbers and large integers work fine.
Choose how many numbers. Use the slider to pick how many numbers to generate in one batch.
Toggle unique numbers if needed. Enable "Unique Numbers Only" to prevent duplicates — useful for raffles, lotteries, and statistical sampling without replacement.
Generate and copy. Click Generate, then copy the output to your clipboard or use the results directly.
Who Is This For?
- →Teachers running classroom random selection — picking students to answer questions or assigning groups without the appearance of favoritism.
- →Developers needing random test data — generating IDs, simulating game outcomes, or seeding test databases with unpredictable values.
- →Event organizers picking giveaway winners — running a fair, defensible random draw for social media contests or live events.
- →Anyone needing fair, unbiased number selection — statistical sampling, tabletop game outcomes, or resolving disputes by chance.
Key Benefits
- ✓Optional browser CSPRNG — pick
crypto.getRandomValues()when you want stronger draws than Math.random (not a hardware TRNG). - ✓Free to use now — ads are not live yet; no subscription, no paywall, no account required.
- ✓No account required — open the page and start generating immediately.
- ✓Uniform distribution — every integer in your range has an exactly equal probability of being selected, with no hidden weighting or bias.
Common Random Number Mistakes
- ✗Using Math.random() for security-sensitive applications — browser Math.random() is a pseudo-random algorithm seeded by a predictable value and should never be used for passwords, tokens, or cryptographic keys.
- ✗Setting a range that's too narrow when picking unique numbers — if you request 10 unique numbers from a range of 1–10, the generator must return every number in the range; a range smaller than your count is impossible.
- ✗Treating "random" as "unbiased across sessions" — each generation is independent; previous results have no influence on the next result, which is correct statistical behavior but surprises people who expect even distribution across small samples.
For security-sensitive random generation, pair this tool with our Password Generator, which also uses crypto.getRandomValues(). For unique identifiers in software projects, the UUID Generator produces RFC 4122-compliant IDs.
For technical documentation on the Web Cryptography API used by this tool, see MDN: Crypto.getRandomValues().
Avoiding Number Duplicates
In many scenarios — like drawing raffle tickets from a hat — a single entry cannot be picked twice. In probability, this is called sampling without replacement.
When you activate "Unique Numbers Only," the generator uses a Fisher-Yates shuffle variant to ensure no value repeats in your output. The count you request must be less than or equal to the total integers in your range.
Uniform Probability Distribution
This tool implements a uniform statistical distribution: every integer in your defined range has the exact same probability of being selected.
There is no hidden weighting, algorithmic bias, or curve. If your range is 1–10, each number has exactly a 10% chance of appearing on any single draw.
Common Use Cases
Contests and giveaways. Assign each participant a number, then generate a winner at random. Selecting crypto.getRandomValues() uses this browser's CSPRNG for the draw — useful for everyday giveaways where you want stronger-than-Math.random picks.
Statistical sampling. Researchers selecting a random subset of participants from a numbered list use tools like this to eliminate selection bias. Unique mode ensures no participant is counted twice.
Game design and tabletop RPGs. Game masters generate encounter tables, random loot, initiative rolls, or NPC assignments using number generators as a base layer for procedural content.
Software testing. Developers use random integers as input values for fuzz testing — feeding unexpected values to application logic to surface edge cases and unexpected behavior.
Frequently Asked Questions
What is a random number generator? ▼
A random number generator produces numbers for everyday draws. This page lets you pick Math.random (fast, not cryptographic) or crypto.getRandomValues() (this browser's CSPRNG). Neither option is a hardware entropy source.
Is this tool free to use? ▼
Yes — free to use now. Ads are not live yet. No account required. It runs in this tab. Tool inputs stay in the browser.
Is this truly random or pseudo-random? ▼
Default draws use Math.random. If you select crypto.getRandomValues(), this browser's CSPRNG supplies the bits. That is strong for browser raffles and sampling, but it is not a hardware TRNG / true-physical-entropy claim. Do not use this page to mint passwords or cryptographic keys.
What is the difference between random and pseudo-random numbers? ▼
Pseudo-random generators (including Math.random) follow a deterministic algorithm. A CSPRNG such as crypto.getRandomValues is designed so outputs are not practically predictable for everyday use. Hardware true-random sources are different; this page does not expose a hardware TRNG.
Can I generate negative random numbers? ▼
Yes. Enter a negative value in the minimum field — for example, -500 — and the generator will produce numbers spanning that range without error.
What happens if I request more unique numbers than my range allows? ▼
The tool will show an error. It is mathematically impossible to generate 50 unique numbers from a range of only 10. The count of unique numbers you request must always be less than or equal to the total integers in your range.
This tool is provided for informational and educational purposes only. Results are not a substitute for professional advice.
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