UUID Validator & Decoder: Version, Variant, Timestamp

Valid 01a1cfb4-de86-70b3-9be3-db1aa67917f6

Version 7 Unix Epoch time-based Sortable by time

01a1cfb4de86 unix_ts_ms

7 ver

0b3 rand_a

9be3db1aa67917f6 var + rand_b

Version	7 Unix Epoch time-based
Variant	RFC 9562 (formerly RFC 4122 / DCE 1.1) (bits `10`)
Timestamp (UTC)	`2026-11-12T12:21:39.590Z` Unix: 1794486099590 ms. Milliseconds.

Version

7 Unix Epoch time-based

Variant

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

Timestamp (UTC)

2026-11-12T12:21:39.590Z
Unix: 1794486099590 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)	`01a1cfb4-de86-70b3-9be3-db1aa67917f6`
Uppercase	`01A1CFB4-DE86-70B3-9BE3-DB1AA67917F6`
Microsoft GUID (braces)	`{01A1CFB4-DE86-70B3-9BE3-DB1AA67917F6}`
URN	`urn:uuid:01a1cfb4-de86-70b3-9be3-db1aa67917f6`
32 hex digits	`01a1cfb4de8670b39be3db1aa67917f6`
Base64 (RFC byte order)	`AaHPtN6GcLOb49sapnkX9g==`
128-bit integer (decimal)	`2169400578734432042869039851898476534`
.NET Guid.ToByteArray() (hex)	`b4cfa10186deb3709be3db1aa67917f6`
.NET Guid bytes (Base64)	`tM+hAYbes3Cb49sapnkX9g==`

Standard (lowercase)

01a1cfb4-de86-70b3-9be3-db1aa67917f6

Uppercase

01A1CFB4-DE86-70B3-9BE3-DB1AA67917F6

Microsoft GUID (braces)

{01A1CFB4-DE86-70B3-9BE3-DB1AA67917F6}

URN

urn:uuid:01a1cfb4-de86-70b3-9be3-db1aa67917f6

32 hex digits

01a1cfb4de8670b39be3db1aa67917f6

Base64 (RFC byte order)

AaHPtN6GcLOb49sapnkX9g==

128-bit integer (decimal)

2169400578734432042869039851898476534

.NET Guid.ToByteArray() (hex)

b4cfa10186deb3709be3db1aa67917f6

.NET Guid bytes (Base64)

tM+hAYbes3Cb49sapnkX9g==

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 01a1cfb4-de86-70b3-9be3-db1aa67917f6 Copy

Formats

How to decode a UUID

Variant digit

Valid `01a1cfb4-de86-70b3-9be3-db1aa67917f6`