UUID Generator

This UUID generator produces version 4 UUIDs using the browser's cryptographically secure random number generator. Generate one or up to 500 at a time, choose uppercase or lowercase, strip the hyphens, or wrap each value in braces for use in C# and SQL Server. Nothing is generated on a server, so the identifiers you copy have never left your machine.

A UUID (universally unique identifier), also called a GUID, is a 128-bit value written as 32 hexadecimal digits in a 8-4-4-4-12 pattern. Version 4 UUIDs are random apart from six fixed bits that mark the version and variant, giving roughly 2¹²² possible values. The practical consequence: you can generate them independently on thousands of machines and never coordinate, and a collision remains vanishingly unlikely.

UUIDs are the default choice for database primary keys in distributed systems, for correlation IDs in logs and traces, for idempotency keys on API requests, and for file names that must not clash. One caveat worth knowing: random v4 UUIDs make poor clustered primary keys in large tables because inserts land in random index positions — if write throughput matters, look at UUIDv7 or a sequential ID with a UUID as a secondary public identifier.