Is this better than Math.random?

For most uses Math.random is fine but it's not cryptographically secure (predictable from previous outputs) and is slightly biased toward smaller numbers. This tool uses crypto.getRandomValues — uniform across the range and unpredictable.

Can I generate without replacement?

Yes — toggle 'unique' to produce N distinct values from the range. Useful for lottery quick-picks or randomly sampling a subset of records.

What's the largest range supported?

Up to 2^53 for integers (JavaScript's Number.MAX_SAFE_INTEGER). Larger ranges work as floats but lose integer precision above that bound. Use BigInt mode if you need true arbitrary-size integers.

ranges · unique picks · local · crypto

Roll random numbers securely

Q: Is anything sent to a server?

No — generation is fully local, using your browser's crypto RNG.

Pick integers from any range, in any count, with optional uniqueness. Backed by crypto.getRandomValues for unbiased draws — all in your browser.

Random Number Generator

Count

1 requested

Sum

Average

—

mean

Output

0 B

idle

input · range

MinMaxCount

Unique values (no repeats)

Uses crypto.getRandomValues for unbiased uniform draws. Max 10 000 per generation.

output · numbers (0)

Click Generate to roll numbers

Quick Start

How to roll fair random numbers

The browser's Web Crypto API gives us uniform random bytes. We modulo into your range with rejection-sampling-like behaviour to stay unbiased.

01
Set the range
Min and Max are inclusive integers.
Inputs are treated as UTF-8 throughout the pipeline and validated client-side as you type — nothing dispatches until the value is well-formed.
rangeinpututf-8client-sidevalidated
min/max · text1/100 · set
```
[1, 100]
```
loaded · parsedclient-side
02
Pick a count
1 to 10 000 numbers per generation.
Each toggle re-computes through a memoised hook, so flipping options never resets your input and the UI stays snappy on large inputs.
countoptionslivememoisedtoggles
n · memoised5 · live
```
count = 5
```
options set · memoisedlive
03
Toggle uniqueness
For draws without replacement check Unique.
Randomness — where used — comes from crypto.getRandomValues, never Math.random. Heavy work sits in useMemo.
uniquecomputeinstantlocaldeterministic
mode · instantunique · computed
```
no repeats
```
computed · instantinstant
04
Copy or download
Plain text, one number per line.
Copy writes through navigator.clipboard and downloads use a Blob — zero network traffic. Same input plus same options always yield the same bytes.
exportcopydownloadzero-networkreproducible
ok · copiedtxt · copied
```
Copied
```
shipped · ready to shipsuccess

Pro tips

Pro tips for everyday utilities

Reach for crypto.getRandomValues

Cryptographically random for IDs, tokens, salts. Math.random is for animation and games, not security.

Sort IDs lexicographically

UUID v4 has no time ordering. Use ULID or UUID v7 if you need sorted IDs.

Mock data with seeds

Faker-style libraries can be seeded so tests are reproducible. Embed the seed in the fixture file.

Reference cards beat memory

Cheatsheets for Vim, Git, Docker, Linux signals are faster than man pages when you’re mid-flow.

Browser APIs vary

Touch events, gamepads, and clipboard differ across vendors. Feature-detect before use.

Persist in the right place

localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data.

Use Cases

When to pull random integers

Sampling, raffles, simulation, testing.

Raffle draws

Pick winners from numbered tickets without repeats. Random values come from crypto.getRandomValues — cryptographically secure for tokens, salts, and session IDs. Math.random is deterministic enough for animations but predictable enough to be a security bug.

CSPRNG-backed

QA fixtures

Seed databases with random IDs for tests. Pair with hashids, ULID, or UUID v7 when you need both random and sortable — useful for primary keys, public-facing IDs, and event log ordering without a sequence column.

reproducible

Statistical sampling

Choose random survey participants. Output is deterministic given the same seed, so fixtures and tests stay reproducible across CI runs and contributor machines. Embed the seed in the fixture file for full replay.

snappy

Game prototyping

Quickly grab dice-like draws while coding. Heavy work runs through useMemo so the UI stays snappy on large inputs. Same input + same options yields identical bytes — the kind of stability snapshot tests rely on.

feature-detected

Simulation seeds

Sanity-check distributions with crypto-grade draws. Storage tools persist to the right backend: localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data. Pick the right shelf and quota worries disappear.

deterministic

Lottery practice

Verify draws against your favourite lottery format. Browser feature detection: clipboard, fullscreen, gamepad, and Web Bluetooth APIs gracefully fall back when unavailable. No surprise white screens on Safari or older Firefox.

production-ready

FAQ

Frequently asked questions

Is this truly random?

It uses the browser's Web Crypto API which derives entropy from OS sources. Suitable for non-cryptographic uses and most cryptographic ones.

Why cap at 10 000?

Larger sets fight pasteboards and UI responsiveness. For huge runs script the API directly.

What about floats?

This tool yields integers only. For floats divide your draw by the range.

Why does unique need range ≥ count?

You can't draw 10 distinct numbers from 3 slots — we surface that error early.

Is anything sent to a server?

No — everything runs locally in your browser.

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Something missing?

Tell us what you need. We ship the top requests every two weeks.

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