What Is a UUID?
A UUID, or Universally Unique Identifier, is a 128-bit value used to uniquely identify records, users, transactions, and resources without a central authority. UUID version 4 is randomly generated, which means the chance of a collision is astronomically small. A UUID generator creates these identifiers instantly, making it a favorite tool for developers who need primary keys, session tokens, or correlation IDs.
How a UUID v4 Is Generated
A version 4 UUID is produced from cryptographically secure random numbers. The string contains 32 hexadecimal characters arranged in five groups separated by hyphens, such as 550e8400-e29b-41d4-a716-446655440000. Certain bits are reserved to mark the value as version 4 and variant 1, which preserves compatibility with the UUID standard while keeping the rest of the value random.
UUID vs. GUID
UUID and GUID are essentially the same concept with different names. Microsoft popularized the term GUID, or Globally Unique Identifier, but both refer to a 128-bit identifier that follows the same format. A GUID generator and a UUID generator therefore produce interchangeable results for most practical purposes.
Why Use a UUID Generator?
- Create unique database keys without a sequence
- Generate session and API tokens
- Assign stable identifiers in distributed systems
- Anonymize records while preserving uniqueness
For other secure random values, check out our password generator or generate random numbers with the random number generator.