UUID Generator
Free UUID generator online — no signup required. Generate cryptographically random UUID v4 values using your browser's built-in crypto API. 100% client-side, zero server calls.
Click Generate to create UUID v4 values
Features
- RFC 4122 compliant UUID v4 generation
- Cryptographically secure using browser's crypto API
- Generate 1 to 100 UUIDs at once
- Toggle uppercase/lowercase output
- Copy single UUID or all UUIDs in one click
- Zero server calls — all generated locally in your browser
Frequently Asked Questions
What is a UUID?
UUID stands for Universally Unique Identifier. It is a 128-bit value typically represented as 32 hex digits grouped as 8-4-4-4-12 separated by hyphens (e.g. 550e8400-e29b-41d4-a716-446655440000). UUIDs are used as unique identifiers in databases, APIs, file systems, and distributed systems.
What is UUID v4?
UUID v4 is a randomly generated UUID. Unlike v1 (time-based) or v3/v5 (name-based), v4 uses random numbers for all 122 bits (the remaining 6 bits indicate the version and variant). It is the most commonly used version and is suitable for any use case where uniqueness without predictability is needed.
Is a UUID truly unique?
A UUID v4 has 2^122 possible values (approximately 5.3 × 10^36). The probability of generating two identical UUIDs is astronomically small — you would need to generate a billion UUIDs per second for 100 years to have a 50% chance of a single collision. For all practical purposes, UUIDs are unique.
What is the difference between UUID and GUID?
GUID (Globally Unique Identifier) is Microsoft's name for UUID. They refer to the same concept and format. GUIDs are used in Windows systems, .NET, and SQL Server, while UUIDs are used in Unix systems, databases like PostgreSQL and MySQL, and web APIs.