Set the count and format options, then hit Generate. Each UUID is individually copyable or you can copy all at once.

Format options

Hyphens — standard xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx format (on by default)
Uppercase — use A–F instead of a–f for the hex digits
Braces — wrap in curly braces like {uuid} (Windows/COM style)

Tip: All UUIDs are generated with crypto.getRandomValues() — cryptographically secure randomness, not Math.random().

Count

Include hyphens

Uppercase

Wrap in braces {...}

Hit Generate to create UUIDs

How UUIDs work

A UUID (Universally Unique Identifier) is a 128-bit number displayed as 32 hex characters in five groups: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. Version 4 fills all bits with random data except two fixed markers — the 4 version nibble and two variant bits. With 122 random bits, collision is practically impossible.

Format breakdown

The five groups split as 8-4-4-4-12 hex digits. The third group's first character is always 4 (version). The fourth group's first character is always 8, 9, a, or b (the variant bits). Everything else is random.

Collision probability

With 122 bits of entropy there are ~5.3 × 10³⁶ possible values. To have a 50% chance of a single collision you'd need ~2.7 quintillion UUIDs — roughly one per person on Earth every second for 85 years. Treat v4 UUIDs as guaranteed unique in practice.

UUID vs GUID

The same thing. UUID is the RFC 4122 standard term. GUID is Microsoft's name — often shown in uppercase with curly braces: {550E8400-…}. They're fully interchangeable. This tool generates lowercase without braces, which is the most widely accepted format.

When to use UUIDs

Database primary keys when rows are created across multiple servers (no central counter needed), distributed system IDs, session tokens, upload file names, and log correlation IDs. Prefer UUIDs over sequential IDs when records must merge across databases without conflicts.