UUID / GUID generator

Create universally unique identifiers for databases, APIs or files. They are generated in your browser with a cryptographically secure random generator.

What is a UUID?

A UUID (Universally Unique Identifier), also called a GUID in the Microsoft world, is a 128-bit identifier written as 32 hexadecimal digits in 8-4-4-4-12 groups, for example 550e8400-e29b-41d4-a716-446655440000. Its big advantage is that it can be generated anywhere, without coordinating with a central database, with a practically zero chance of collision.

UUID v4 or UUID v7

UUID v4 has 122 random bits and is the most widely used. UUID v7 (RFC 9562, 2024) starts with the date and time in milliseconds, so identifiers are sorted chronologically. This makes it much more efficient as a database primary key, because indexes do not get fragmented when new rows are inserted.

The version number is the first digit of the third group: in …-7b41-… it is a 7.

What about ULID?

A ULID (Universally Unique Lexicographically Sortable Identifier) also combines 48 bits of time and 80 random bits, but it is written as 26 characters in Crockford's base 32 (without I, L, O or U to avoid confusion), for example 01J9ZQ3K8M4X7V2B6N5C1D0E9F. It is shorter than a UUID and is also sorted by time.