UUID Generator

What does this UUID Generator do?

This tool generates version 4 UUIDs (Universally Unique Identifiers) as defined by RFC 4122 — 128-bit values almost universally used in software to identify records, sessions, or objects without needing a central authority to hand out IDs.

How it works

A version 4 UUID is essentially 122 random bits formatted into the standard 8-4-4-4-12 hyphenated hex pattern (e.g., f47ac10b-58cc-4372-a567-0e02b2c3d479), with a few fixed bits marking it as version 4. This generator uses the browser's built-in crypto.randomUUID() function where available, which draws from a cryptographically secure random source.

Why UUIDs rarely collide

With 122 random bits, there are roughly 5.3 × 10³⁶ possible version 4 UUIDs. Even generating billions of UUIDs, the probability of ever generating a duplicate by chance is astronomically small — which is exactly why UUIDs are trusted as identifiers in distributed systems without needing a central registry.

Tips & common mistakes

• UUIDs are not sequential or sortable by generation time (unlike some other ID schemes) — if you need time-ordered IDs, a different scheme like ULID may be more appropriate.
• Don't rely on a UUID's format alone for security purposes — while collision is extremely unlikely, a UUID is not inherently a secret and shouldn't be treated as if guessing it were impossible in an adversarial context.

Frequently asked questions