🆔 UUID Validator

By ToolNimba Web Dev Team · Updated 2026-06-19

UUID to validate

Enter a UUID above and press Validate.

A UUID (Universally Unique Identifier), also called a GUID on Microsoft platforms, is a 128-bit value written as 32 hexadecimal digits in the 8-4-4-4-12 pattern. This validator checks whether the string you paste is structurally well-formed, then reads its structure to report the version (1 to 5) and the variant. Paste a UUID with or without surrounding braces and get an instant verdict, all in your browser.

What is the UUID Validator?

A UUID is a 128-bit identifier designed to be unique without a central authority handing out numbers. It is normally written as 36 characters: 32 hexadecimal digits split into five groups of 8, 4, 4, 4 and 12, separated by hyphens, for example 123e4567-e89b-12d3-a456-426614174000. Microsoft calls the same thing a GUID and often wraps it in braces, like {123e4567-e89b-12d3-a456-426614174000}. Validating a UUID means confirming it matches that canonical shape, which this tool does with a single regular expression.

Beyond the shape, two specific digits carry meaning. The first digit of the third group is the version, a value from 1 to 5 in RFC 4122. Version 1 is time-based, built from a timestamp and a node identifier. Versions 3 and 5 are name-based, hashing a namespace plus a name with MD5 and SHA-1 respectively. Version 4 is purely random and is by far the most common in modern software. The first digit of the fourth group encodes the variant: when it falls in the range 8 to b it signals the standard RFC 4122 layout, while c to d marks the older Microsoft variant.

It is worth being clear about what validation does and does not prove. A well-formed UUID is syntactically correct, but that says nothing about whether it was generated correctly, whether it is truly unique in your system, or whether it points at any real record. A string can pass the format check and still be a placeholder, a duplicate, or a test value. Use this tool to catch typos, wrong lengths, stray characters and misplaced hyphens, not to guarantee that an identifier is meaningful.

When to use it

Confirming a UUID copied from a log, database row or API response is well-formed before you use it.
Checking which version a UUID is (random v4 versus time-based v1) when debugging an integration.
Validating a Microsoft GUID that arrives wrapped in braces, without manually stripping them first.
Spotting typos, transposed characters or wrong lengths in identifiers pasted from documentation.

How to use the UUID Validator

Paste or type the UUID you want to check into the input field.
Leave any surrounding braces in place if you have them, they are accepted and stripped automatically.
Press Validate (or just type, it checks as you go).
Read off the verdict, the detected version, and the variant.

Formula & method

A canonical UUID matches the pattern 8-4-4-4-12 hex digits: xxxxxxxx-xxxx-Vxxx-Nxxx-xxxxxxxxxxxx, where each x is a hex digit (0-9, a-f), V (position 13) is the version 1 to 5, and N (position 17) is the variant digit (8 to b for RFC 4122).

Worked examples

You paste f47ac10b-58cc-4372-a567-0e02b2c3d479 and want to know its version and variant.

Check the shape: 8-4-4-4-12 hex digits separated by hyphens. It matches.
Read the version digit, the first character of the third group (4372): it is 4.
Version 4 means a random UUID (122 random bits).
Read the variant digit, the first character of the fourth group (a567): it is a.
a is in the range 8 to b, so the variant is RFC 4122.

Result: Valid UUID, version 4 (random), RFC 4122 variant.

You paste {6ba7b810-9dad-11d1-80b4-00c04fd430c8} copied from a Windows registry export.

The string is wrapped in braces, so strip the leading { and trailing }.
Check the remaining 6ba7b810-9dad-11d1-80b4-00c04fd430c8 against the 8-4-4-4-12 pattern. It matches.
Version digit (first char of third group, 11d1): 1, so it is time-based.
Variant digit (first char of fourth group, 80b4): 8, which is in 8 to b, so RFC 4122.

Result: Valid UUID, version 1 (time-based), RFC 4122 variant, braces accepted.

UUID versions defined by RFC 4122

Version digit	Type	How it is built
1	Time-based	Timestamp plus a node identifier (often the MAC address)
2	DCE Security	Like v1 but embeds a POSIX UID or GID
3	Name-based (MD5)	MD5 hash of a namespace UUID plus a name
4	Random	122 random or pseudo-random bits
5	Name-based (SHA-1)	SHA-1 hash of a namespace UUID plus a name

Variant from the first digit of the fourth group

Digit	Variant
0 to 7	NCS backward compatibility (legacy)
8 to b	RFC 4122 (the standard layout)
c to d	Microsoft reserved (legacy GUID)
e to f	Reserved for future use

Common mistakes to avoid

Treating a valid format as a real, unique identifier. Passing the format check only means the string has the right shape. It does not prove the UUID is unique, was generated correctly, or maps to any actual record in your system.
Rejecting a GUID just because it has braces. Microsoft GUIDs are often written wrapped in {curly braces}. The braces are a presentation convention, not part of the value. This validator strips a matching pair before checking.
Confusing the version digit with a random hex digit. The 13th character (first of the third group) is always the version. A genuine v4 UUID has a 4 there and one of 8, 9, a or b at the variant position. If those are off, the UUID may have been built by hand or by a faulty generator.
Assuming any 32 hex digits make a UUID. The hyphens and their positions matter for the canonical form. A run of 32 hex digits with no hyphens, or hyphens in the wrong place, is not a well-formed UUID even if the digit count is correct.

Glossary

UUID: Universally Unique Identifier, a 128-bit value written as 32 hex digits in the 8-4-4-4-12 pattern.
GUID: Globally Unique Identifier, Microsoft's name for a UUID, often shown wrapped in braces.
Version: A digit from 1 to 5 (the 13th character) that tells you how the UUID was generated.
Variant: Bits in the 17th character that define the layout, with 8 to b indicating the RFC 4122 standard.
RFC 4122: The specification that defines the standard UUID format, versions and variants.
Hexadecimal: Base-16 notation using the digits 0-9 and letters a-f, the only characters allowed in a UUID.

Frequently asked questions

What makes a string a valid UUID?

A valid UUID is 32 hexadecimal digits (0-9, a-f) arranged in five hyphen-separated groups of 8, 4, 4, 4 and 12 characters, for example 123e4567-e89b-12d3-a456-426614174000. This validator checks that exact pattern and accepts an optional pair of surrounding braces.

What is the difference between a UUID and a GUID?

They are the same concept: a 128-bit unique identifier. UUID is the name used in RFC 4122 and across most platforms, while GUID is Microsoft's term, frequently written inside curly braces. This tool validates both and strips the braces for you.

How do I find out which version a UUID is?

Look at the 13th character, the first digit of the third group. A value of 1 to 5 is the version: 1 is time-based, 3 and 5 are name-based, 4 is random, and 2 is DCE Security. The validator reads this digit and tells you the version automatically.

Why does my UUID show an unknown version?

If the version digit is 0 or higher than 5, it falls outside the standard range defined by RFC 4122. The string may still match the overall shape, but it was likely generated by hand or by a non-standard tool rather than a compliant UUID library.

Is a UUID case sensitive?

No. UUIDs are usually written in lowercase, but uppercase hex digits are equally valid. This validator accepts either and shows you the normalized lowercase form so you can compare values consistently.

Does a valid format mean the UUID is unique?

No. Validation only confirms the string is well-formed. Uniqueness depends on how the value was generated and managed in your system. A correctly formatted UUID can still be a duplicate, a placeholder, or a test value, so format alone is no guarantee.