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 01a1d81d-a2a9-720d-939a-d829ff42fb21

Version 7 Unix Epoch time-based Sortable by time
01a1d81da2a9 unix_ts_ms
7 ver
20d rand_a
939ad829ff42fb21 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-11-14T03:33:03.273Z
Unix: 1794627183273 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) 01a1d81d-a2a9-720d-939a-d829ff42fb21
Uppercase 01A1D81D-A2A9-720D-939A-D829FF42FB21
Microsoft GUID (braces) {01A1D81D-A2A9-720D-939A-D829FF42FB21}
URN urn:uuid:01a1d81d-a2a9-720d-939a-d829ff42fb21
32 hex digits 01a1d81da2a9720d939ad829ff42fb21
Base64 (RFC byte order) AaHYHaKpcg2Tmtgp/0L7IQ==
128-bit integer (decimal) 2169571138441543450370124494932212513
.NET Guid.ToByteArray() (hex) 1dd8a101a9a20d72939ad829ff42fb21
.NET Guid bytes (Base64) HdihAamiDXKTmtgp/0L7IQ==

API: /api/decode/01a1d81d-a2a9-720d-939a-d829ff42fb21

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.