UUID Generator

For most applications, UUID v4 (random) is the best default. For databases where sort order matters, UUID v7 (timestamp + random) provides chronological ordering with better index performance.

Astronomically low. You'd need to generate 2.7 quintillion (2.7×10¹⁸) UUIDs to have a 50% chance of one collision. At 1 billion UUIDs per second, that's 86 years.

UUIDs work well as primary keys but v4 causes B-tree fragmentation due to randomness. UUID v7 or ULID solve this with timestamp prefixes that maintain insert order.

UUIDs are 128-bit identifiers in 8-4-4-4-12 hex format. ULIDs are also 128-bit but use a 48-bit timestamp + 80-bit random component in a compact, sortable base32 encoding (26 characters vs UUID's 36).

Yes, the nil UUID (00000000-0000-0000-0000-000000000000) is a valid UUID defined in RFC 4122. It is typically used as a sentinel or default value meaning "no UUID assigned."