UUID Generator
Generate UUID v4 identifiers using the browser crypto RNG — crypto.randomUUID where available, a vetted fallback elsewhere. Bulk batches, optional uppercase, custom dash style.
What is a UUID v4?
A 128-bit identifier rendered as 8-4-4-4-12 hex digits; version 4 means 122 of the bits are random (6 bits fix the version/variant fields). Collision odds are astronomically small — you would need to generate ~2.7 quintillion v4 UUIDs for a 50% chance of one duplicate. The generator uses crypto.randomUUID() when available, otherwise a fallback built on crypto.getRandomValues() — never Math.random(), which is predictable.
How to use UUID Generator
Choose a version and a count, then generate: v4 draws from the cryptographic random source, while v7 trades some randomness for a time-sortable prefix that indexes better in databases. Lowercase or uppercase, with or without hyphens, and the batch copies as newline-separated output in one click.
Use v4 unless you have a specific reason not to; reach for v7 when IDs become database keys or URL slugs where creation order matters. Keys are unique within a batch by construction, and with 122 random bits, cross-batch collisions stay a non-event at any realistic volume.
Frequently asked questions
What is the difference between UUID v4 and v7?
v4 is fully random and unguessable, ideal for public identifiers. v7 embeds a millisecond timestamp prefix that keeps database indexes compact and insertions sequential.
How unique is UUID v4 really?
With 122 random bits, a duplicate is essentially impossible in practice: you would need billions upon billions of generated UUIDs before a collision becomes plausible.
Are UUIDs safe to expose publicly?
They are unguessable but not secrets. Access control must never rely on the difficulty of guessing an ID — that is authorization, not obscurity.
Can I generate many UUIDs at once?
Yes. Pick a count from one to hundreds, choose a format (standard, no hyphens, braces or uppercase) and copy the whole batch in one click, generated through the crypto API locally.