UUID Generator
Generate one or many UUID v4 values instantly using cryptographically secure randomness. Copy to clipboard or download as a plain text file.
Frequently Asked Questions
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify information in computer systems. It is displayed as 32 hexadecimal digits in five groups separated by hyphens, such as 550e8400-e29b-41d4-a716-446655440000. UUIDs let independent systems create identifiers without a central coordinator, eliminating the risk of duplicate keys across distributed databases.
What is UUID v4?
UUID v4 is generated entirely from cryptographically random numbers — 122 bits of randomness with a few reserved bits indicating the version (4) and variant. Because the randomness comes from a cryptographically secure source, the probability of two v4 UUIDs ever colliding is astronomically small. This makes them safe to use as database primary keys without any prior collision check.
What are UUIDs used for in software development?
UUIDs work as primary keys in databases where records are created across multiple servers without a shared sequence generator. They also serve as session tokens, upload filenames, idempotency keys in payment APIs, and identifiers in event-driven architectures where multiple services create records independently and later synchronise them without key conflicts.