UUID Validator & Decoder: Version, Variant, Timestamp

Valid 01a1d1b9-019d-724b-b7cf-1ea6f0aecf41

Version 7 Unix Epoch time-based Sortable by time

01a1d1b9019d unix_ts_ms

7 ver

24b rand_a

b7cf1ea6f0aecf41 var + rand_b

Version	7 Unix Epoch time-based
Variant	RFC 9562 (formerly RFC 4122 / DCE 1.1) (bits `10`)
Timestamp (UTC)	`2026-11-12T21:45:25.149Z` Unix: 1794519925149 ms. Milliseconds.

Version

7 Unix Epoch time-based

Variant

RFC 9562 (formerly RFC 4122 / DCE 1.1) (bits 10)

Timestamp (UTC)

2026-11-12T21:45:25.149Z
Unix: 1794519925149 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)	`01a1d1b9-019d-724b-b7cf-1ea6f0aecf41`
Uppercase	`01A1D1B9-019D-724B-B7CF-1EA6F0AECF41`
Microsoft GUID (braces)	`{01A1D1B9-019D-724B-B7CF-1EA6F0AECF41}`
URN	`urn:uuid:01a1d1b9-019d-724b-b7cf-1ea6f0aecf41`
32 hex digits	`01a1d1b9019d724bb7cf1ea6f0aecf41`
Base64 (RFC byte order)	`AaHRuQGdcku3zx6m8K7PQQ==`
128-bit integer (decimal)	`2169441471326077569148809998830063425`
.NET Guid.ToByteArray() (hex)	`b9d1a1019d014b72b7cf1ea6f0aecf41`
.NET Guid bytes (Base64)	`udGhAZ0BS3K3zx6m8K7PQQ==`

Standard (lowercase)

01a1d1b9-019d-724b-b7cf-1ea6f0aecf41

Uppercase

01A1D1B9-019D-724B-B7CF-1EA6F0AECF41

Microsoft GUID (braces)

{01A1D1B9-019D-724B-B7CF-1EA6F0AECF41}

URN

urn:uuid:01a1d1b9-019d-724b-b7cf-1ea6f0aecf41

32 hex digits

01a1d1b9019d724bb7cf1ea6f0aecf41

Base64 (RFC byte order)

AaHRuQGdcku3zx6m8K7PQQ==

128-bit integer (decimal)

2169441471326077569148809998830063425

.NET Guid.ToByteArray() (hex)

b9d1a1019d014b72b7cf1ea6f0aecf41

.NET Guid bytes (Base64)

udGhAZ0BS3K3zx6m8K7PQQ==

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 digit	Meaning	Contains a timestamp?
1	Gregorian time-based	Yes (100 ns since 1582)
2	DCE Security	Partial
3	Name-based, MD5	No
4	Random	No
5	Name-based, SHA-1	No
6	Reordered Gregorian time	Yes (100 ns since 1582)
7	Unix Epoch time	Yes (ms since 1970)
8	Custom	Only if your format has one

Variant digit

Binary	Hex digit	Variant
`0xxx`	0 - 7	Reserved, NCS backward compatibility
`10xx`	8 - b	RFC 9562 (the standard variant)
`110x`	c - d	Reserved, Microsoft backward compatibility
`111x`	e - f	Reserved 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.

UUID Validator & Decoder

Valid 01a1d1b9-019d-724b-b7cf-1ea6f0aecf41 Copy

Formats

How to decode a UUID

Variant digit

Valid `01a1d1b9-019d-724b-b7cf-1ea6f0aecf41`