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 01a1b5fd-cddf-72a6-be03-a9cf4acf8e72

Version 7 Unix Epoch time-based Sortable by time
01a1b5fdcddf unix_ts_ms
7 ver
2a6 rand_a
be03a9cf4acf8e72 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-11-07T12:31:11.839Z
Unix: 1794054671839 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) 01a1b5fd-cddf-72a6-be03-a9cf4acf8e72
Uppercase 01A1B5FD-CDDF-72A6-BE03-A9CF4ACF8E72
Microsoft GUID (braces) {01A1B5FD-CDDF-72A6-BE03-A9CF4ACF8E72}
URN urn:uuid:01a1b5fd-cddf-72a6-be03-a9cf4acf8e72
32 hex digits 01a1b5fdcddf72a6be03a9cf4acf8e72
Base64 (RFC byte order) AaG1/c3fcqa+A6nPSs+Ocg==
128-bit integer (decimal) 2168879014586959079101701358181387890
.NET Guid.ToByteArray() (hex) fdb5a101dfcda672be03a9cf4acf8e72
.NET Guid bytes (Base64) /bWhAd/NpnK+A6nPSs+Ocg==

API: /api/decode/01a1b5fd-cddf-72a6-be03-a9cf4acf8e72

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.