UUID Generator
Generate random UUIDs (v4) and other UUID versions.
Frequently Asked Questions
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hexadecimal digits in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are designed to be unique across space and time without requiring a central authority. They are also known as GUIDs (Globally Unique Identifiers) in Microsoft systems.
What is the difference between UUID versions?
UUID v1 uses the current timestamp and MAC address. UUID v4 (most common) uses random numbers for all significant bits, providing 122 bits of randomness. UUID v5 generates a deterministic UUID from a namespace and name using SHA-1. This tool generates v4 by default — the most widely used version for unique identifiers.
How unique are UUID v4 values really?
With 122 random bits, there are 5.3 x 10^36 possible UUID v4 values. The probability of generating two identical UUIDs is astronomically low — you would need to generate 2.71 x 10^18 UUIDs to have a 50% chance of a single collision. For all practical purposes, every UUID v4 is guaranteed to be unique.
Can I generate multiple UUIDs at once?
Yes — specify the number of UUIDs to generate (up to 1,000) and get them all instantly. You can copy the entire batch with one click. Format options include standard lowercase, uppercase, with or without dashes, and with curly braces for Microsoft GUID format.
Where are UUIDs commonly used?
UUIDs are used as database primary keys (avoiding sequential ID exposure), API request IDs, session tokens, file names for uploaded content, distributed system identifiers, and anywhere you need a unique identifier without coordinating with a central server. They are fundamental to modern distributed systems.