UUID Generator

How to generate a UUID

1. Click Generate UUID for a fresh random version-4 ID, or type a count and hit Generate batch for up to 1,000 at once.
2. Copy what you need. Each bulk row has its own Copy button; Copy all grabs the whole batch as newline-separated text.
3. Pick your case. Lowercase is the canonical RFC 4122 form and what most databases expect — but the toggle is there if your system wants uppercase.

When to use a UUID

UUIDs shine wherever IDs must be unique without a central authority: distributed database primary keys, API request IDs, session tokens, unique filenames, and test fixtures. Because version 4 is random, two services can mint IDs independently and essentially never collide — there are 2¹²² possible values, more than atoms in the observable universe have UUIDs to spare.

Don't use a UUID where a human needs to read or type the ID (order numbers, short links) — for those, a short random string or sequential number is friendlier.

UUID v4 vs. other versions

v4 (this tool) is purely random — simple and safe. v1 embeds a timestamp and MAC address (leaks machine info; rarely what you want). v7 is the new time-ordered variant, great for database indexes. If your database supports v7 natively, prefer it for primary keys; otherwise v4 is the universal default.

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit label written as 32 hexadecimal digits in five groups, like f47ac10b-58cc-4372-a567-0e02b2c3d479. Version 4 UUIDs are random, so two independently generated IDs will essentially never collide.

How random are these UUIDs?

In secure browser contexts this tool uses crypto.randomUUID(), the browser's cryptographic random number generator. If your browser or page context does not support it, the tool falls back to crypto.getRandomValues or Math.random and shows a warning; the fallback IDs are still unique-shaped but not cryptographic.

Can I use these UUIDs as database primary keys?

Yes. UUID v4 is the standard choice for distributed primary keys because no central server needs to hand out IDs. Most databases (PostgreSQL, MySQL, MongoDB) accept them directly.

What is the difference between uppercase and lowercase UUIDs?

None functionally. The canonical RFC 4122 form is lowercase, and most software expects lowercase, but parsers treat both the same. The toggle just changes display.

Are my UUIDs sent anywhere?

No. Generation happens entirely in your browser with JavaScript. Nothing is uploaded, stored, or tracked.