UUID Generator

About this tool

Version-4 UUIDs are 128-bit identifiers generated from random data, giving an astronomically low chance of collision. They're ideal for database keys, request IDs and distributed systems. This generator uses your browser's cryptographic random source and can produce up to 1,000 at once.

Common use cases

• Generate database IDs — Create unique primary keys for database records without collisions
• Test API endpoints — Generate random UUIDs for testing REST APIs that require UUID parameters
• Create session tokens — Generate unique identifiers for user sessions or tracking cookies

How it works

UUID v4 (Universally Unique Identifier version 4) is a 128-bit identifier generated using random or pseudo-random numbers. The format is 8-4-4-4-12 hexadecimal characters (36 chars total with hyphens). Version 4 sets the version nibble to 4 and the variant nibble to 8, 9, A, or B. The probability of a collision is astronomically low — about 1 in 10^36 for two random UUIDs.

FAQ

Are these UUIDs cryptographically random?

Yes — they use the browser's crypto.getRandomValues / randomUUID, a secure random source, not Math.random.

What is a v4 UUID?

A universally unique identifier generated from random bits, formatted as 8-4-4-4-12 hexadecimal characters.

Will two UUIDs ever collide?

The probability is negligible — you'd need billions of UUIDs before a collision becomes remotely likely.

Are UUID v4 truly random?

UUID v4 uses 122 bits of randomness (6 bits are reserved for version and variant). Good implementations use cryptographically secure random number generators.

Can I use UUID as database primary key?

Yes, but be aware that random UUIDs can cause index fragmentation in some databases. Consider UUID v7 (time-ordered) for better database performance.