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Free Online UUID Generator

Generate cryptographically random UUID v4 identifiers instantly. Create single or bulk UUIDs with one click using secure crypto.getRandomValues().

What Is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier that is practically guaranteed to be unique. UUIDs are formatted as 32 hexadecimal digits in five hyphen-separated groups. They are used for database keys, session IDs, and distributed systems.

UUID v4 — Random Generation

UUID version 4 uses cryptographically secure random numbers via crypto.getRandomValues(). The 13th hex digit is always 4 (version) and the 17th is always 8, 9, a, or b (variant), as per RFC 4122.

When to Use UUIDs

UUIDs are ideal for unique identifiers without a central authority: database primary keys, API request tracking, file naming, session tokens, and message queue identifiers.

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Frequently Asked Questions

What is the chance of a UUID collision?
Extremely low. You would need about 2.71 quintillion UUIDs for a 50% collision chance. For practical purposes, UUID v4 values are unique.
What is the difference between UUID and GUID?
They are the same thing. GUID is Microsoft's term, UUID is the standard term from RFC 4122. Both are 128-bit identifiers.
Why does the UUID have specific digits?
The 13th hex digit is always 4 (version 4) and the 17th is always 8, 9, a, or b (variant). This is defined by RFC 4122.
Are these UUIDs cryptographically secure?
Yes. This tool uses crypto.getRandomValues() for cryptographically secure random numbers, generated entirely in your browser.
Can I use UUIDs as database primary keys?
Yes, commonly used in distributed databases. They are larger than auto-increment integers but guarantee uniqueness without coordination.

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