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 01a1c8b1-2f3a-718a-9282-b2359f7f1735

Version 7 Unix Epoch time-based Sortable by time
01a1c8b12f3a unix_ts_ms
7 ver
18a rand_a
9282b2359f7f1735 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-11-11T03:40:17.594Z
Unix: 1794368417594 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) 01a1c8b1-2f3a-718a-9282-b2359f7f1735
Uppercase 01A1C8B1-2F3A-718A-9282-B2359F7F1735
Microsoft GUID (braces) {01A1C8B1-2F3A-718A-9282-B2359F7F1735}
URN urn:uuid:01a1c8b1-2f3a-718a-9282-b2359f7f1735
32 hex digits 01a1c8b12f3a718a9282b2359f7f1735
Base64 (RFC byte order) AaHIsS86cYqSgrI1n38XNQ==
128-bit integer (decimal) 2169258309930967822731070060734912309
.NET Guid.ToByteArray() (hex) b1c8a1013a2f8a719282b2359f7f1735
.NET Guid bytes (Base64) scihATovinGSgrI1n38XNQ==

API: /api/decode/01a1c8b1-2f3a-718a-9282-b2359f7f1735

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.