UUIDTools.com

UUID Validator & Decoder

Paste a UUID or GUID to check it and see what is inside: version, variant, timestamp and more.

Accepts hyphenated, 32 hex digits, {braces}, urn:uuid:, any case. Try a fresh v7.

Valid 01a187d1-13bf-72f1-8fde-4c85d63dda47

Version 7 Unix Epoch time-based Sortable by time
01a187d113bf unix_ts_ms
7 ver
2f1 rand_a
8fde4c85d63dda47 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-10-29T13:19:48.671Z
Unix: 1793279988671 ms. Milliseconds.

Version 7 UUIDs start with a 48-bit Unix timestamp in milliseconds followed by random bits, so they sort by creation time.

Formats

Standard (lowercase) 01a187d1-13bf-72f1-8fde-4c85d63dda47
Uppercase 01A187D1-13BF-72F1-8FDE-4C85D63DDA47
Microsoft GUID (braces) {01A187D1-13BF-72F1-8FDE-4C85D63DDA47}
URN urn:uuid:01a187d1-13bf-72f1-8fde-4c85d63dda47
32 hex digits 01a187d113bf72f18fde4c85d63dda47
Base64 (RFC byte order) AaGH0RO/cvGP3kyF1j3aRw==
128-bit integer (decimal) 2167942480103144401814133810552232519
.NET Guid.ToByteArray() (hex) d187a101bf13f1728fde4c85d63dda47
.NET Guid bytes (Base64) 0YehAb8T8XKP3kyF1j3aRw==

API: /api/decode/01a187d1-13bf-72f1-8fde-4c85d63dda47

How to decode a UUID

Every RFC 9562 UUID stores its version in the 13th hex digit and its variant in the top bits of the 17th digit:

xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx
             M = version (1-8)   N = variant (8, 9, a, b = RFC 9562)
Version digitMeaningContains a timestamp?
1Gregorian time-basedYes (100 ns since 1582)
2DCE SecurityPartial
3Name-based, MD5No
4RandomNo
5Name-based, SHA-1No
6Reordered Gregorian timeYes (100 ns since 1582)
7Unix Epoch timeYes (ms since 1970)
8CustomOnly if your format has one

Variant digit

BinaryHex digitVariant
0xxx0 - 7Reserved, NCS backward compatibility
10xx8 - bRFC 9562 (the standard variant)
110xc - dReserved, Microsoft backward compatibility
111xe - fReserved for future definition

The decoder never throws on odd input: unknown versions, legacy variants and the special nil (00000000-…) and max (ffffffff-…) UUIDs all produce a readable result.

Learn more in UUID versions explained.