UUID Generator | SparkJSON

Count (max 1000)

Uppercase

Hyphens

0 UUIDs (v4)

Quick answers

Are these UUIDs actually random, or is there a pattern?
They're generated by crypto.randomUUID(), which uses a cryptographically secure random number generator provided by your browser and operating system — the same category of randomness used for generating encryption keys, not a simple pseudo-random pattern.
Why is there a limit of 1,000 UUIDs per batch?
It's a practical UI limit, not a security one — generating and rendering tens of thousands of rows at once would make the page sluggish for no real benefit. If you need more, just click generate again.

About UUID Generator

Generate one or up to 1,000 version-4 UUIDs at once using the browser's crypto.randomUUID(), with optional uppercase or hyphen-free formatting and one-click copy for a single ID or the whole batch.

Every UUID here comes from crypto.randomUUID(), the Web Crypto API's built-in version-4 UUID generator. It's backed by your operating system's cryptographically secure random number source, which matters if these IDs will ever be used for anything where predictability is a risk — session tokens, invite codes, or database primary keys where you don't want the next ID to be guessable.

Version 4 means the UUID is (almost) entirely random: 122 of its 128 bits are random, with the remaining 6 fixed to mark the version and variant per RFC 4122. That gives roughly 5.3 undecillion possible values, so collisions are not a practical concern even generating the full 1,000-at-a-time batch this tool allows.

The formatting toggles only change presentation — stripping hyphens or upper-casing the hex digits — and don't touch the underlying randomness or the RFC 4122 bit layout.

Frequently asked questions

Are these UUIDs actually random, or is there a pattern?

They're generated by crypto.randomUUID(), which uses a cryptographically secure random number generator provided by your browser and operating system — the same category of randomness used for generating encryption keys, not a simple pseudo-random pattern.

Why is there a limit of 1,000 UUIDs per batch?

It's a practical UI limit, not a security one — generating and rendering tens of thousands of rows at once would make the page sluggish for no real benefit. If you need more, just click generate again.

What's the difference between UUID v4 and other versions?

UUID versions differ in how their bits are derived. Version 1 encodes a timestamp and (traditionally) a MAC address, version 5 is a deterministic hash of a namespace and name, and version 4 — what this tool generates — is (almost) fully random, which makes it the right default when you just need a unique, unpredictable identifier.