UUID Validator & Decoder Online – Check Version and Time

How to use the UUID Validator & Decoder

Paste your UUIDs or GUIDs, one per line. Braces, urn:uuid: prefixes and hyphen-less forms are accepted.

Validation runs automatically; click Validate to refresh after edits.

Check the status line for how many lines are valid.

Read the version, variant and decoded time under each valid UUID, and the reason next to each ✘.

UUID validator and decoder

This UUID validator checks that each line is a well-formed UUID and then tells you what kind it is. It reads the version and variant bits, decodes the timestamp hidden in version 1, 6 and 7 UUIDs, and shows the same value as a URN, Base64 and ULID. It works for Microsoft GUIDs too, since a GUID is the same 128-bit format.

Example

Input:

0192a4c1-7e2b-7d4a-9b1c-3f5e8a2d6c01
{123e4567-e89b-12d3-a456-42661417400}

Output:

0192a4c1-7e2b-7d4a-9b1c-3f5e8a2d6c01
  ✔ Valid UUID  0192a4c1-7e2b-7d4a-9b1c-3f5e8a2d6c01
  Version:  7 — Unix-time-based, sortable (random tail)
  Variant:  RFC 9562 / RFC 4122 (standard)
  Time:     2024-10-19T12:29:57.163Z
  URN:      urn:uuid:0192a4c1-7e2b-7d4a-9b1c-3f5e8a2d6c01
  Base64:   AZKkwX4rfUqbHD9eii1sAQ==
  As ULID:  01JAJC2ZHBFN59P71ZBT52TV01

{123e4567-e89b-12d3-a456-42661417400}
  ✘ Not a UUID: expected 32 hex digits (8-4-4-4-12).

The second value looks right at a glance, but its last group has 11 digits instead of 12. The time line in the tool also shows how long ago the UUID was created.

What is checked

Format: exactly 32 hexadecimal digits. Hyphens are optional, but if present they must split the value 8-4-4-4-12. Surrounding braces and a urn:uuid: prefix are stripped first; upper and lower case are both fine.
Special values: the Nil UUID (all zeros) and the Max UUID (all f, introduced in RFC 9562) are recognized.
Variant: the high bits of the 17th hex digit. Standard UUIDs have 8, 9, a or b there; other values mean legacy NCS, Microsoft-reserved or future variants.
Version: the 13th hex digit, from 1 to 8.

UUID versions explained

Version	Contents	Decoded here
1	Gregorian timestamp (100 ns units since 1582) + clock sequence + node	Time, clock sequence, node / MAC
3 / 5	MD5 / SHA-1 hash of a namespace and name	Version only
4	122 random bits	Version only
6	Version 1 fields reordered so the value sorts by time	Time, clock sequence, node
7	48-bit Unix millisecond timestamp + random bits	Time
8	Custom, vendor-specific layout	Version only

For v1 and v6, the node is labeled "MAC address" or "random, multicast bit set". Most modern libraries set the multicast bit and use a random node rather than exposing the real network card address.

Common reasons a UUID fails validation

A missing or extra digit, often from a truncated copy or a typo in test data.
Hyphens in the wrong place, such as 550e8400-e29b41d4-a716-446655440000. The tool reports "Hyphens are in the wrong places".
Non-hex characters like g–z, or look-alikes such as the letter O instead of zero.
Not a UUID at all: a 26-character ULID or a 24-character MongoDB ObjectId. Use the ULID decoder for the first.

A value can be well-formed yet have an unusual version or variant — for example a ULID stored in UUID form. The validator accepts it but labels the version accordingly, so you can spot IDs that were not produced by a standard UUID library. Need new IDs? The UUID generator creates v4 and time-ordered UUIDs, and the Unix timestamp converter helps you compare decoded times.

Privacy

Validation and decoding run in your browser, up to 1,000 lines at a time. The UUIDs you paste are not sent to a server or logged.

Frequently asked questions

Is a GUID the same as a UUID?

Yes. GUID is Microsoft’s name for the same 128-bit identifier, and GUIDs generated by Windows and .NET are normally standard version 4 UUIDs. They are often written in uppercase or inside braces, which this validator accepts.

How can I tell which version a UUID is?

Look at the first digit of the third group: in 0192a4c1-7e2b-7d4a-… it is 7, so the UUID is version 7. The validator reads that digit for you and names the version.

Can I get the creation time from a UUID v4?

No. Version 4 UUIDs are random apart from the version and variant bits, so they contain no time. Only versions 1, 6 and 7 carry a timestamp that can be decoded.

Does it accept UUIDs without hyphens?

Yes. A 32-digit hex string is validated and shown in the canonical 8-4-4-4-12 form. If hyphens are present, they must be in exactly those positions.

Why is my UUID valid but shown with a non-standard variant?

The 17th hex digit decides the variant. If it is not 8, 9, a or b, the value was not produced by an RFC 9562 generator — for example a ULID in UUID form or a hand-made test value. The format is still a valid 128-bit UUID.

UUID Validator & Decoder