UUID Generator

UUID (Universally Unique Identifier) is a 128-bit label used to identify information in computer systems. A UUID looks like 550e8400-e29b-41d4-a716-446655440000. There are approximately 5.3 × 10^36 possible UUIDs — the chance of generating two identical UUIDs is astronomically small (about 1 in 10^18 for a trillion v4 UUIDs). UUIDs are used as primary keys in databases, session tokens, file names, and API identifiers.

UUID v1: time-based, includes the MAC address of the machine. Sortable chronologically but leaks machine information — less private. UUID v4: completely random, using cryptographically secure random numbers. The most widely used version — no information about the generating machine. UUID v7: a newer standard (RFC 9562, 2024), time-ordered like v1 but uses random bits instead of MAC address. Sortable and database-index-friendly without leaking system info.

For most use cases: UUID v4 is the safe default — random, private, well-supported everywhere. Use UUID v7 for database primary keys when you want chronological sortability (improves index performance in PostgreSQL, MySQL, etc.). Avoid v1 in new applications as it exposes your MAC address. For distributed systems where ordering matters, v7 is quickly becoming the new standard as of 2024.