Bulk UUID / GUID Generator
Generate unique RFC 4122 Version 4 (Random) and Version 1 (Time-based) UUIDs. Configure casing, braces, and delimiters locally.
Frequently Asked Questions
What is a UUID / GUID?
A Universally Unique Identifier (UUID), also known as a Globally Unique Identifier (GUID) in Windows environments, is a 128-bit label used for resources in computer systems. Standard UUID formatting represents these 128 bits as 32 hexadecimal digits separated by hyphens in a 8-4-4-4-12 configuration (e.g. f4802422-5c35-4db8-bbf7-d05b0d01j2h9).
Version 4 vs. Version 1 UUIDs
Different algorithms (or versions) govern how UUIDs are constructed:
- Version 4 (Random): Generated entirely from pseudo-random numbers (122 random bits and 6 version bits). It is the most common format because it does not leak host MAC addresses or timestamp history.
- Version 1 (Time-Based): Constructed from the host system's hardware MAC address (node) and a 60-bit timestamp tracking 100-nanosecond ticks. It is useful when ordering identifiers chronologically is important.
Collision Probability & Math
Because Version 4 UUIDs have 122 bits of absolute randomness, the total number of possible combinations is 2122 (or about 5.3 Undecillion keys). The chance of a single collision is so microscopically small that generating billions of UUIDs every second for a century would result in a negligible collision probability. It is mathematically safe to assume they are universally unique.