UUID generator
Random version-4 UUIDs, generated securely on your device. Crypto-random
How to use the UUID generator
- The page greets you with five fresh UUIDs — click Generate whenever you want a new batch.
- Set How many you need (1–500); out-of-range values are clamped, and the results appear one UUID per line.
- Shape the output with the format options: Uppercase, wrap in { } (the style Windows registry entries and SQL Server GUIDs use), or no hyphens for systems that store the compact 32-character form.
- Choose your format before settling on IDs — changing any option regenerates the batch with new values rather than restyling the current ones.
- Copy all puts the newline-separated list on your clipboard, ready for a seed script or a spreadsheet column.
Common uses
- Fill test fixtures: generate 100 unique IDs for a load-test CSV or a database seed script in one click.
- Grab a primary key or correlation ID to paste into an API request you're composing in Postman or curl.
- Mint idempotency keys for payment or job APIs that deduplicate requests by unique ID.
- Produce GUIDs in the braced form for Windows registry work or SQL Server
uniqueidentifiercolumns, without hand-typing braces. - Tag a filename, bucket or backup with an identifier that's guaranteed not to collide with anything you've used before.
Tips & limitations
- Format first, copy second: toggling Uppercase, braces or hyphens generates new UUIDs — there's no way to reformat a batch you already have.
- These are version 4 (fully random) UUIDs only. If you want time-sortable v7 IDs for database index locality, or deterministic name-based v5, generate those in code with a library — this page doesn't make them.
- Case never changes meaning: UUIDs are case-insensitive and lowercase is the canonical form, so the Uppercase option is purely cosmetic for style guides that want it.
- A UUID makes a great identifier but a mediocre secret — IDs routinely end up in URLs and log files. When you need a credential, use a password generator and keep IDs and secrets separate.
How it's built & why it's safe
Each UUID starts as 16 bytes from crypto.getRandomValues() — the cryptographically secure random generator built into your browser — then two small bit-edits stamp the version (4) and variant fields required by RFC 4122, leaving 122 bits of pure randomness. Formatting into the familiar 8-4-4-4-12 shape happens in the same few lines of local JavaScript. Nothing is fetched from or sent to a server and nothing is stored, so no one — this site included — ever sees the IDs you generate.
Related tools: Password Generator · Hash Generator · Lorem Ipsum · Random Picker
Further reading: What makes a password strong? Entropy, length and passphrases
Frequently asked questions
What kind of UUIDs are these?
Version 4, variant 1 UUIDs as described by RFC 4122: 128 bits, of which 122 are random and 6 are fixed version/variant markers. They come from the browser's cryptographically secure random source, not the weaker Math.random().
Are they guaranteed unique?
Not by a registry — by probability. With 122 random bits you could generate a billion UUIDs every second for decades before a duplicate becomes at all likely, which is why v4 UUIDs are trusted as database keys everywhere.
Can it make v1, v5 or v7 UUIDs?
No — this generator produces random v4 only. Time-based v1, name-based v5 and the newer sortable v7 each need extra inputs like timestamps or namespaces, and are best generated by a library in your own code.
Why did the whole list change when I toggled a checkbox?
The format options re-run the generator rather than restyle the existing list, so every toggle produces brand-new IDs. Decide on uppercase, braces and hyphens first, then generate and copy.
Are the UUIDs sent anywhere or logged?
No — they're created by your browser's own crypto API and exist only on this page until you copy them. There's no server-side generation, no history and no storage, so nobody can associate an ID with you later.
Is a UUID random enough to use as a password or token?
The 122 bits come from a cryptographically secure source, so the raw entropy is strong. But UUIDs are treated as non-secret in practice — logged, indexed, exposed in URLs — so use a password generator for credentials and keep identifiers separate from secrets.