UUID Generator
Generate random, RFC-4122-compliant version 4 UUIDs, one or in bulk.
How unique is a UUID v4?
A version 4 UUID has 122 random bits. Even generating a billion per second, a collision would take far longer than the age of the universe to become likely.
Where UUIDs are used
Database primary keys in distributed systems (where auto-increment IDs can collide across nodes), session tokens, request-tracing IDs, and file names that must never clash are all common uses.
Common Mistakes to Avoid
Assuming UUIDs are sequential or sortable
Solution:
Version 4 UUIDs are fully random — they carry no time ordering. If you need sortable unique IDs, look at ULIDs or a database sequence instead.
Using a UUID as a security token
Solution:
UUIDs are designed for uniqueness, not secrecy. For something like a password-reset token, use a value generated specifically for cryptographic security.
Frequently Asked Questions
Theoretically yes, but the probability is so low it is treated as effectively zero for any practical use case.
No — UUIDs are generated entirely in your browser using the Web Crypto API.
How unique is a UUID v4?
A version 4 UUID has 122 random bits. Even generating a billion per second, a collision would take far longer than the age of the universe to become likely.
Where UUIDs are used
Database primary keys in distributed systems (where auto-increment IDs can collide across nodes), session tokens, request-tracing IDs, and file names that must never clash are all common uses.