UUID v4 Generator
Generate RFC 4122 version-4 UUIDs (random) individually or in bulk. Pure client-side, no server hit.
Last updated: April 2026 · Runs in your browser · No sign-up
- 1688eb21-385e-49ff-84f7-e62e347f230b
Frequently Asked Questions
What is a UUID v4?
A universally unique identifier generated from 122 random bits (6 bits are reserved for version and variant). Standard format: 8-4-4-4-12 hex characters.
Is UUID v4 truly unique?
Not guaranteed — but the collision probability is so low (~2^-61 after a quintillion IDs) that in practice it's considered unique. Uses crypto.randomUUID() where available.
When should I use UUID v7 instead?
UUID v7 is time-ordered, making database indexes more efficient. Use v7 for primary keys in large tables; use v4 for opaque IDs where ordering doesn't matter.
Can I use UUIDs in URLs?
Yes — they're URL-safe (only hex digits and hyphens). Some teams strip hyphens to save 4 bytes: both forms are accepted by parsers.
Are these UUIDs predictable?
No. This tool uses the Web Crypto API (crypto.randomUUID or crypto.getRandomValues) — cryptographically random, not predictable.