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 01a1b7ff-cde9-721c-a51f-2761efec5e42

Version 7 Unix Epoch time-based Sortable by time
01a1b7ffcde9 unix_ts_ms
7 ver
21c rand_a
a51f2761efec5e42 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-11-07T21:52:37.353Z
Unix: 1794088357353 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) 01a1b7ff-cde9-721c-a51f-2761efec5e42
Uppercase 01A1B7FF-CDE9-721C-A51F-2761EFEC5E42
Microsoft GUID (braces) {01A1B7FF-CDE9-721C-A51F-2761EFEC5E42}
URN urn:uuid:01a1b7ff-cde9-721c-a51f-2761efec5e42
32 hex digits 01a1b7ffcde9721ca51f2761efec5e42
Base64 (RFC byte order) AaG3/83pchylHydh7+xeQg==
128-bit integer (decimal) 2168919737874578121722986601812614722
.NET Guid.ToByteArray() (hex) ffb7a101e9cd1c72a51f2761efec5e42
.NET Guid bytes (Base64) /7ehAenNHHKlHydh7+xeQg==

API: /api/decode/01a1b7ff-cde9-721c-a51f-2761efec5e42

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.