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 b4ecfd42-cf84-21f1-bd00-63410362b4e9

Version 2 DCE Security
b4ecfd42 local_id
cf84 time_mid
2 ver
1f1 time_high
bd var + clock_seq
00 local_domain
63410362b4e9 node
Version2 DCE Security
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-10-24T08:22:06.7828736Z
Unix: 1792830126 s. Approximate: the low 32 bits of the timestamp are replaced by the local identifier, so the true time is up to ~7 minutes later.
Clock sequence61
Node63:41:03:62:b4:e9 Random node ID (multicast bit set; not a real MAC address)
Local domainPerson (POSIX UID) (0)
Local identifier3035430210

Version 2 (DCE Security) is reserved by RFC 9562 but its layout is defined by the DCE 1.1 spec. It is rarely used.

Formats

Standard (lowercase) b4ecfd42-cf84-21f1-bd00-63410362b4e9
Uppercase B4ECFD42-CF84-21F1-BD00-63410362B4E9
Microsoft GUID (braces) {B4ECFD42-CF84-21F1-BD00-63410362B4E9}
URN urn:uuid:b4ecfd42-cf84-21f1-bd00-63410362b4e9
32 hex digits b4ecfd42cf8421f1bd0063410362b4e9
Base64 (RFC byte order) tOz9Qs+EIfG9AGNBA2K06Q==
128-bit integer (decimal) 240491558042810661795667818956068140265
.NET Guid.ToByteArray() (hex) 42fdecb484cff121bd0063410362b4e9
.NET Guid bytes (Base64) Qv3stITP8SG9AGNBA2K06Q==

API: /api/decode/b4ecfd42-cf84-21f1-bd00-63410362b4e9

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.