UUID Generator
Generate RFC 4122 version 4 UUIDs instantly in bulk.
How to Use
- Set the quantity (1 to 100 UUIDs).
- Choose a format: standard, uppercase, no hyphens, or wrapped in braces.
- Click Generate.
- Click Copy All or select individual UUIDs from the list.
When to Use This
- Primary keys you need to assign before a record reaches the database, so an insert does not have to wait for an auto-increment value to come back.
- Idempotency keys on API requests, so a client can safely retry a call without the server processing it twice.
- Correlation or trace IDs that follow one request across several services and appear in every log line it touches.
- Filenames for uploaded files, where two people submitting photo.jpg must not overwrite one another.
Frequently Asked Questions
About This Tool
A UUID version 4 is a 128-bit identifier in which 122 bits are random and the remaining 6 are fixed to mark the version and variant. That randomness is the whole point: two systems can each mint identifiers forever, without ever communicating, and still not collide in practice.
This generator calls your browser's crypto.randomUUID() where it exists and falls back to crypto.getRandomValues() where it does not. Both draw on the operating system's cryptographically secure random source rather than Math.random(), so the output is suitable for identifiers that need to be unguessable as well as unique. Everything happens on your device, nothing is transmitted, and reloading the page produces an entirely fresh set.
Notes & Limits
- A v4 UUID contains no timestamp, so a set of them cannot be sorted into creation order. Use UUID v7 if you need identifiers that sort by time.
- Random 128-bit keys scatter across a B-tree index. On large tables that fragments writes, which is why some databases prefer sequential IDs or UUID v7 for a clustered primary key.
- Collision probability is negligible, not zero, at roughly 1 in 5.3 x 10^36 for any given pair. A UUID is not a substitute for a uniqueness constraint.
- A UUID is unguessable but it is not a secret. Treat it as an identifier, never as an access token.