What is a UUID?
A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 32 hex digits in five groups, e.g. 3f50a6c1-9b2e-4d7a-8f10-c2b4e9d10f33. It is used as a globally unique key without a central authority.
What is a version-4 UUID?
Version 4 UUIDs are generated from random data. This tool uses the browser's cryptographically secure random source, so collisions are astronomically unlikely.
Are UUIDs guaranteed unique?
Not strictly guaranteed, but the probability of a collision among v4 UUIDs is so small it is negligible for virtually every application — you would need billions of UUIDs before any meaningful risk.
Can I use these as database primary keys?
Yes. UUIDs are popular primary keys because they can be generated by clients without coordinating with the database. Note that random UUIDs can fragment B-tree indexes; consider UUIDv7 or ULIDs if insert order matters.
