UUID Validator & Decoder: Version, Variant, Timestamp

Valid 01a1d2c1-612f-70a1-8958-778ff9b4ca31

Version 7 Unix Epoch time-based Sortable by time

01a1d2c1612f unix_ts_ms

7 ver

0a1 rand_a

8958778ff9b4ca31 var + rand_b

Version	7 Unix Epoch time-based
Variant	RFC 9562 (formerly RFC 4122 / DCE 1.1) (bits `10`)
Timestamp (UTC)	`2026-11-13T02:34:11.119Z` Unix: 1794537251119 ms. Milliseconds.

Version

7 Unix Epoch time-based

Variant

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

Timestamp (UTC)

2026-11-13T02:34:11.119Z
Unix: 1794537251119 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)	`01a1d2c1-612f-70a1-8958-778ff9b4ca31`
Uppercase	`01A1D2C1-612F-70A1-8958-778FF9B4CA31`
Microsoft GUID (braces)	`{01A1D2C1-612F-70A1-8958-778FF9B4CA31}`
URN	`urn:uuid:01a1d2c1-612f-70a1-8958-778ff9b4ca31`
32 hex digits	`01a1d2c1612f70a18958778ff9b4ca31`
Base64 (RFC byte order)	`AaHSwWEvcKGJWHeP+bTKMQ==`
128-bit integer (decimal)	`2169462417138552575964429592454023729`
.NET Guid.ToByteArray() (hex)	`c1d2a1012f61a1708958778ff9b4ca31`
.NET Guid bytes (Base64)	`wdKhAS9hoXCJWHeP+bTKMQ==`

Standard (lowercase)

01a1d2c1-612f-70a1-8958-778ff9b4ca31

Uppercase

01A1D2C1-612F-70A1-8958-778FF9B4CA31

Microsoft GUID (braces)

{01A1D2C1-612F-70A1-8958-778FF9B4CA31}

URN

urn:uuid:01a1d2c1-612f-70a1-8958-778ff9b4ca31

32 hex digits

01a1d2c1612f70a18958778ff9b4ca31

Base64 (RFC byte order)

AaHSwWEvcKGJWHeP+bTKMQ==

128-bit integer (decimal)

2169462417138552575964429592454023729

.NET Guid.ToByteArray() (hex)

c1d2a1012f61a1708958778ff9b4ca31

.NET Guid bytes (Base64)

wdKhAS9hoXCJWHeP+bTKMQ==

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 01a1d2c1-612f-70a1-8958-778ff9b4ca31 Copy

Formats

How to decode a UUID

Variant digit

Valid `01a1d2c1-612f-70a1-8958-778ff9b4ca31`