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 01a1c9f9-c2a7-729e-ae6f-610f0e7135de

Version 7 Unix Epoch time-based Sortable by time
01a1c9f9c2a7 unix_ts_ms
7 ver
29e rand_a
ae6f610f0e7135de var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-11-11T09:39:11.143Z
Unix: 1794389951143 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) 01a1c9f9-c2a7-729e-ae6f-610f0e7135de
Uppercase 01A1C9F9-C2A7-729E-AE6F-610F0E7135DE
Microsoft GUID (braces) {01A1C9F9-C2A7-729E-AE6F-610F0E7135DE}
URN urn:uuid:01a1c9f9-c2a7-729e-ae6f-610f0e7135de
32 hex digits 01a1c9f9c2a7729eae6f610f0e7135de
Base64 (RFC byte order) AaHJ+cKncp6ub2EPDnE13g==
128-bit integer (decimal) 2169284342394346952823060151992923614
.NET Guid.ToByteArray() (hex) f9c9a101a7c29e72ae6f610f0e7135de
.NET Guid bytes (Base64) +cmhAafCnnKub2EPDnE13g==

API: /api/decode/01a1c9f9-c2a7-729e-ae6f-610f0e7135de

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.