๐ UUID Validator
Enter a UUID (universally unique identifier, in the 8-4-4-4-12 hex digit format) to validate its format and determine the version number and variant defined by RFC 4122.
How to use
- Enter the UUID you want to validate.
- Whether itโs correctly formatted, along with its version and variant, is shown automatically.
How the calculation works
A UUID (universally unique identifier) is a 128-bit identifier written as 32 hex digits in 8-4-4-4-12 groups, such as 550e8400-e29b-41d4-a716-446655440000. It was defined in RFC 4122, superseded in 2024 by RFC 9562. This tool first checks the format, then reads two fields. Version: the first character of the third group. 1 is time and MAC address, 3 an MD5 hash, 4 random, 5 a SHA-1 hash, and 6 and 7 the newer time-ordered versions added in RFC 9562. Variant: the first character of the fourth group. 8, 9, a or b means the standard RFC 4122/9562 layout; 0โ7 the old NCS layout; c or d the Microsoft layout. Upper- and lower-case hex are both accepted.
Worked example
Input: 550e8400-e29b-41d4-a716-446655440000 Third group 41d4 โ version 4 (random) Fourth group a716 โ a, the standard variant Input: 00000000-0000-0000-0000-000000000000 The all-zero "nil UUID" has a valid format and shows as version 0. Input: 550e8400e29b41d4a716446655440000 (no hyphens) โ format error
Things to be aware of
- This tool only checks the format and version fields; it cannot tell whether a UUID is actually in use or was generated correctly.
- Braces ({...}) and URN form (urn:uuid:...) are not accepted as is. Remove the braces or prefix first.
- For database primary keys, version 7 is handy because it sorts in time order.
FAQ
What is a UUID version?
A number (1โ8) indicating how the UUID was generated. For example, version 4 means random generation, while version 1 means timestamp- and MAC-address-based generation.
What is a variant?
A classification of the UUIDโs internal layout. Nearly all UUIDs in wide use today are the standard variant defined by RFC 4122.
Can this check for duplicates?
No. This tool only validates whether the input string is correctly formatted as a UUID. Checking for actual duplicates within your system requires a separate check.