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 01a1c5a2-b6c4-73f8-a822-41c3b9a9cd57

Version 7 Unix Epoch time-based Sortable by time
01a1c5a2b6c4 unix_ts_ms
7 ver
3f8 rand_a
a82241c3b9a9cd57 var + rand_b
Version7 Unix Epoch time-based
VariantRFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)
Timestamp (UTC)2026-11-10T13:25:37.604Z
Unix: 1794317137604 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) 01a1c5a2-b6c4-73f8-a822-41c3b9a9cd57
Uppercase 01A1C5A2-B6C4-73F8-A822-41C3B9A9CD57
Microsoft GUID (braces) {01A1C5A2-B6C4-73F8-A822-41C3B9A9CD57}
URN urn:uuid:01a1c5a2-b6c4-73f8-a822-41c3b9a9cd57
32 hex digits 01a1c5a2b6c473f8a82241c3b9a9cd57
Base64 (RFC byte order) AaHForbEc/ioIkHDuanNVw==
128-bit integer (decimal) 2169196316227038718176073103698414935
.NET Guid.ToByteArray() (hex) a2c5a101c4b6f873a82241c3b9a9cd57
.NET Guid bytes (Base64) osWhAcS2+HOoIkHDuanNVw==

API: /api/decode/01a1c5a2-b6c4-73f8-a822-41c3b9a9cd57

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.