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 01a18cfa-5375-71fd-9e17-2737bab0b8d4

Version 7 Unix Epoch time-based Sortable by time
01a18cfa5375 unix_ts_ms
7 ver
1fd rand_a
9e172737bab0b8d4 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-10-30T13:22:58.037Z
Unix: 1793366578037 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) 01a18cfa-5375-71fd-9e17-2737bab0b8d4
Uppercase 01A18CFA-5375-71FD-9E17-2737BAB0B8D4
Microsoft GUID (braces) {01A18CFA-5375-71FD-9E17-2737BAB0B8D4}
URN urn:uuid:01a18cfa-5375-71fd-9e17-2737bab0b8d4
32 hex digits 01a18cfa537571fd9e172737bab0b8d4
Base64 (RFC byte order) AaGM+lN1cf2eFyc3urC41A==
128-bit integer (decimal) 2168047160223401362937952109241350356
.NET Guid.ToByteArray() (hex) fa8ca1017553fd719e172737bab0b8d4
.NET Guid bytes (Base64) +oyhAXVT/XGeFyc3urC41A==

API: /api/decode/01a18cfa-5375-71fd-9e17-2737bab0b8d4

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.