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 01a18cfb-53da-72fd-b0e7-16196f0f5a48

Version 7 Unix Epoch time-based Sortable by time
01a18cfb53da unix_ts_ms
7 ver
2fd rand_a
b0e716196f0f5a48 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-10-30T13:24:03.674Z
Unix: 1793366643674 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) 01a18cfb-53da-72fd-b0e7-16196f0f5a48
Uppercase 01A18CFB-53DA-72FD-B0E7-16196F0F5A48
Microsoft GUID (braces) {01A18CFB-53DA-72FD-B0E7-16196F0F5A48}
URN urn:uuid:01a18cfb-53da-72fd-b0e7-16196f0f5a48
32 hex digits 01a18cfb53da72fdb0e716196f0f5a48
Base64 (RFC byte order) AaGM+1Pacv2w5xYZbw9aSA==
128-bit integer (decimal) 2168047239573670108705414785098799688
.NET Guid.ToByteArray() (hex) fb8ca101da53fd72b0e716196f0f5a48
.NET Guid bytes (Base64) +4yhAdpT/XKw5xYZbw9aSA==

API: /api/decode/01a18cfb-53da-72fd-b0e7-16196f0f5a48

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.