🪪 Identifier

UUID

Version	Input	Use Case	Notes
v1	Time + MAC address	Avoid	Privacy concerns because the MAC address
v2	Time + POSIX UID/GID (DCE)	Avoid
v3	Namespace UUID + name (string)	Avoid, use UUIDv5 instead	Deterministic, MD5 hashing
v4	Random bits	General purpose unique identifiers	Consider using UUIDv7
v5	Namespace UUID + name (string)	Need deterministic	Deterministic, SHA-1 hashing
v6	Reordered time + MAC address	Avoid, use UUIDv7 instead	Privacy concerns because the MAC address
v7	Unix timestamp + random bits	General purpose unique identifiers	Time-ordered
v8	Custom	Rarely used	User-defined format

Nano ID

Small, secure, URL-friendly.

ai/nanoid0 (0)