The UUID Generator creates cryptographically random UUID v4 (Universally Unique Identifiers) instantly in your browser using the Web Crypto API. Generate single or bulk UUIDs (up to 100 at once), toggle between uppercase and lowercase, and choose whether to include hyphens. UUIDs are essential for database primary keys, distributed systems, session tokens, and any scenario requiring globally unique identifiers without a central authority. All generation happens locally - no UUIDs are stored or transmitted.
Choose how many UUIDs to generate (1-100), whether to include hyphens (standard format: 8-4-4-4-12), and whether to output in uppercase or lowercase.
Press the Generate button to create your UUID(s) instantly. Each UUID is generated using crypto.randomUUID(), which provides cryptographically strong randomness.
Click the copy button next to any UUID to copy just that one, or use 'Copy All' to copy all generated UUIDs separated by newlines.
Click Generate again for fresh UUIDs. Each generation creates entirely new random identifiers. There's no limit to how many you can generate.
A UUID (Universally Unique Identifier) is a 128-bit identifier represented as 32 hexadecimal digits in the format 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). UUID v4 is generated using random numbers, making collision probability astronomically low - about 1 in 2^122.
While not mathematically guaranteed to be unique, the probability of generating duplicate UUID v4 values is so low it's considered impossible in practice. You would need to generate 1 billion UUIDs per second for about 85 years to have a 50% chance of a single collision.
GUID (Globally Unique Identifier) is Microsoft's implementation of UUIDs. They are functionally identical - noth are 128-bit identifiers in the same format. The terms are often used interchangeably. Microsoft tools typically say GUID, while the rest of the industry uses UUID.
UUIDs work well as primary keys in distributed systems where auto-incrementing integers can't coordinate across servers. Downsides include larger storage (16 bytes vs 4-8), no natural ordering, and potential index fragmentation. Consider UUID v7 (time-ordered) for better database performance, or use UUIDs alongside integer IDs.
UUID v4 generated with crypto.randomUUID() uses cryptographically secure random numbers. They are suitable for non-sensitive identifiers. However, don't use UUIDs as security tokens or passwords - while unpredictable, they weren't designed as secrets. Use dedicated token generation for authentication.