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 01a1df31-9d51-7239-a81a-21f87aa5a1c2

Version 7 Unix Epoch time-based Sortable by time
01a1df319d51 unix_ts_ms
7 ver
239 rand_a
a81a21f87aa5a1c2 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-11-15T12:32:13.137Z
Unix: 1794745933137 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) 01a1df31-9d51-7239-a81a-21f87aa5a1c2
Uppercase 01A1DF31-9D51-7239-A81A-21F87AA5A1C2
Microsoft GUID (braces) {01A1DF31-9D51-7239-A81A-21F87AA5A1C2}
URN urn:uuid:01a1df31-9d51-7239-a81a-21f87aa5a1c2
32 hex digits 01a1df319d517239a81a21f87aa5a1c2
Base64 (RFC byte order) AaHfMZ1RcjmoGiH4eqWhwg==
128-bit integer (decimal) 2169714698218209589250750882775409090
.NET Guid.ToByteArray() (hex) 31dfa101519d3972a81a21f87aa5a1c2
.NET Guid bytes (Base64) Md+hAVGdOXKoGiH4eqWhwg==

API: /api/decode/01a1df31-9d51-7239-a81a-21f87aa5a1c2

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.