UUID Generator — Random Version 4 UUIDs, Free & Offline

Random version 4 UUIDs (GUIDs) generated with your browser's cryptographic RNG. Press R for a new one, C to copy.

password

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Time to crack — by who is attacking, and how the site stored it

You don't get to choose which column applies — the site does, when it decides how to store your password. Assume the worst one. Rates are stated so you can check the arithmetic rather than trust it.

Length 20

Characters

lowercasea–z uppercaseA–Z digits0–9 symbols!@#$%^&*()-_=+[]{};:,.<>?/~

Rules the site forced on you

at least one of each type Only tick this if a site demands it. It removes possibilities, so it very slightly lowers entropy — the figure above already accounts for that. no lookalike characters Drops Il1|O0oB8S5Z2G6q9g. Useful when it will be read aloud, typed from paper, or set on a TV. shell & CSV safe Drops quotes, backticks, $, \ and friends, so it survives a script, a YAML file or a connection string.

NIST SP 800-63B-4 forbids sites from imposing composition rules — the guidance now says verifiers shall not require a mixture of character types. Plenty of sites never got the memo, so the switches are here; they just aren't the point.

Words 6

Separator

Extras

Capitalise Each Word Adds nothing an attacker doesn't expect, but some sites insist on a capital. add a digit For sites that demand a number. Worth about 5 bits — a seventh word would be worth 13. add a symbol Same story: satisfies a rule rather than an attacker.

▸ Words are drawn from the EFF long wordlist — exactly 7,776 words, so every word is worth precisely 12.92 bits no matter which one comes up. That is what makes the entropy figure above a fact rather than a guess. Six words beats a twelve-character random password, and you can actually remember it.

Digits 6

⚠ A PIN is for a device that locks after a handful of wrong tries — a phone, a SIM, a door. Read the rate-limited column and ignore the rest: a 6-digit PIN is a million options, which is fine behind a lockout and hopeless anywhere else. Never use a PIN as a website password.

Format

Bytes 32

uppercase hexA–F instead of a–f. Same entropy.

▸ Tokens are drawn straight from crypto.getRandomValues() with no modulo bias. A 128-bit token (16 bytes, 32 hex characters) can't be guessed; 256 bits is the usual choice for session secrets and signing keys.

How many 10

Uses the settings from the password tab. Each one is generated independently.

⚠ A downloaded file is a plaintext list of passwords sitting in your Downloads folder. Move them into a password manager and delete the file — don't leave it there, and don't email it.

Type or paste a password to analyse

This runs in the page. There is no server to send it to — open your network tab and watch, or turn off your Wi-Fi and try it. It is still not a good idea to paste a password you use into any website, including this one.

▸ Nothing here is transmitted. Generation, analysis and the breach check all run in this page using crypto.getRandomValues() and a word list that ships with it. There is no backend, no logging and no analytics event that carries what you generate. The page loads an anonymous, cookie-free page-view counter and nothing else.

Guide — how to use the uuid generator

Generated in your browser with crypto.getRandomValues(); nothing is sent anywhere.

1Open the page

A UUID is generated as soon as it loads, in the standard 8-4-4-4-12 layout.

2Press R for a new one

Each press is a fresh, independent UUID.

3Press C to copy

Paste it into your database, config or code.

4Need many?

Use the bulk tab: it uses the password settings, so for lists of UUIDs generate them one at a time or script crypto.randomUUID().

Questions and answers

What is a UUID v4?

A 128-bit identifier in which 122 bits are random and 6 bits mark the version and variant. It is the format used as a GUID in most systems.

Can two generated UUIDs collide?

In practice no. With 122 random bits you would need to generate about 2.7 quintillion UUIDs to have a 50% chance of one repeated pair.

Is a UUID secure enough as a secret token?

Version 4 UUIDs from a cryptographic RNG have 122 random bits, which is plenty. But do not expose them as identifiers if guessing one would grant access: use a longer token from the token tab for that.

What is the difference between UUID and GUID?

Nothing practical. GUID is the Microsoft name for the same 128-bit format.

Does it work offline?

Yes. After the page has loaded it needs no network, and nothing is sent anywhere.

Want the full story on entropy, crack times and what NIST SP 800-63B says? See the complete random password generator, which also includes a password checker and bulk export.

uuid generator_

Guide — how to use the uuid generator

Questions and answers

What is a UUID v4?

Can two generated UUIDs collide?

Is a UUID secure enough as a secret token?

What is the difference between UUID and GUID?

Does it work offline?

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