UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify information in computer systems. It is formatted as 32 hexadecimal digits separated by hyphens into five groups: 8-4-4-4-12. UUIDs are designed to be unique across space and time without requiring a central authority.

UUID v4 is randomly generated — all 122 bits are random, making each UUID unpredictable. UUID v7 is time-ordered — the first 48 bits encode a Unix timestamp in milliseconds, followed by random bits. This makes v7 UUIDs lexicographically sortable by creation time, which is better for database index performance. Use v4 when you need pure randomness; use v7 when you need sortable IDs.

UUID v4 has 2^122 possible values (~5.3 × 10^36), making the probability of a collision effectively zero in practice. UUID v7 combines a millisecond timestamp with 74 random bits, also making collisions negligible. This tool generates UUIDs entirely in your browser using the cryptographically secure Web Crypto API via the uuid library.

No. All UUIDs are generated entirely in your browser using JavaScript and the Web Crypto API. No data is transmitted to any server. Your generated UUIDs remain completely private.

UUIDs are widely used as primary keys in databases, identifiers for distributed system resources, session tokens, correlation IDs for logging and tracing, filenames for uploaded assets, and IDs in REST or GraphQL APIs. UUID v7 is increasingly preferred for database primary keys because its time-ordered nature reduces B-tree index fragmentation.