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 a216e5f4-cebe-11f1-a415-99df782a71e9

Version 1 Gregorian time-based
a216e5f4 time_low
cebe time_mid
1 ver
1f1 time_high
a415 var + clock_seq
99df782a71e9 node
Version1 Gregorian time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-10-23T08:49:18.3713780Z
Unix: 1792745358 s. Exact to 100 nanoseconds.
Clock sequence9237
Node99:df:78:2a:71:e9 Random node ID (multicast bit set; not a real MAC address)

Version 1 UUIDs reveal when they were made and, unless the multicast bit is set, the MAC address of the machine that made them. For new systems RFC 9562 recommends v7.

Formats

Standard (lowercase) a216e5f4-cebe-11f1-a415-99df782a71e9
Uppercase A216E5F4-CEBE-11F1-A415-99DF782A71E9
Microsoft GUID (braces) {A216E5F4-CEBE-11F1-A415-99DF782A71E9}
URN urn:uuid:a216e5f4-cebe-11f1-a415-99df782a71e9
32 hex digits a216e5f4cebe11f1a41599df782a71e9
Base64 (RFC byte order) ohbl9M6+EfGkFZnfeCpx6Q==
128-bit integer (decimal) 215453829915498719997912791260200595945
.NET Guid.ToByteArray() (hex) f4e516a2becef111a41599df782a71e9
.NET Guid bytes (Base64) 9OUWor7O8RGkFZnfeCpx6Q==

API: /api/decode/a216e5f4-cebe-11f1-a415-99df782a71e9

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.