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 cfbff0d1-9375-5685-968c-48ce8b15ae17

Version 5 Name-based (SHA-1)
cfbff0d19375 hash
5 ver
685 hash
968c48ce8b15ae17 var + hash
Version5 Name-based (SHA-1)
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)

Version 5 UUIDs are a SHA-1 hash of a namespace and a name. The hash cannot be reversed, but the same namespace and name always produce this same UUID.

Formats

Standard (lowercase) cfbff0d1-9375-5685-968c-48ce8b15ae17
Uppercase CFBFF0D1-9375-5685-968C-48CE8B15AE17
Microsoft GUID (braces) {CFBFF0D1-9375-5685-968C-48CE8B15AE17}
URN urn:uuid:cfbff0d1-9375-5685-968c-48ce8b15ae17
32 hex digits cfbff0d193755685968c48ce8b15ae17
Base64 (RFC byte order) z7/w0ZN1VoWWjEjOixWuFw==
128-bit integer (decimal) 276146808210084729002700941631111409175
.NET Guid.ToByteArray() (hex) d1f0bfcf75938556968c48ce8b15ae17
.NET Guid bytes (Base64) 0fC/z3WThVaWjEjOixWuFw==

API: /api/decode/cfbff0d1-9375-5685-968c-48ce8b15ae17

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.