UUID Generator

What is a UUID and what is it used for?

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122, represented as 32 grouped hexadecimal characters (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx). The probability of collision is statistically negligible: for UUID v4, you would need to generate 2.71 quintillion UUIDs to have a 50% chance of a collision.

UUID v4 vs UUID v7

UUID v4 is entirely random (CSPRNG) — ideal for web resource identifiers where order doesn't matter. UUID v7 is the new version (RFC 9562, 2024): the first 48 bits encode the Unix timestamp in milliseconds, making UUIDs naturally sortable. It's the recommended choice for database primary keys (better B-tree indexing performance).

ULID and NanoID: modern alternatives

ULID (Universally Unique Lexicographically Sortable Identifier) encodes a timestamp in 48 bits + 80 random bits in 26 Crockford Base32 characters — lexicographically sorted, URL-safe. NanoID is a compact alternative to UUIDs: 21 characters by default, customizable alphabet, 5× faster than UUID v4 and ideal for short URLs.