UUID Validator & Decoder: Version, Variant, Timestamp

Valid 01a1d666-6583-72c8-ae9c-bec0dd89d193

Version 7 Unix Epoch time-based Sortable by time

01a1d6666583 unix_ts_ms

7 ver

2c8 rand_a

ae9cbec0dd89d193 var + rand_b

Version	7 Unix Epoch time-based
Variant	RFC 9562 (formerly RFC 4122 / DCE 1.1) (bits `10`)
Timestamp (UTC)	`2026-11-13T19:33:17.315Z` Unix: 1794598397315 ms. Milliseconds.

Version

7 Unix Epoch time-based

Variant

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

Timestamp (UTC)

2026-11-13T19:33:17.315Z
Unix: 1794598397315 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)	`01a1d666-6583-72c8-ae9c-bec0dd89d193`
Uppercase	`01A1D666-6583-72C8-AE9C-BEC0DD89D193`
Microsoft GUID (braces)	`{01A1D666-6583-72C8-AE9C-BEC0DD89D193}`
URN	`urn:uuid:01a1d666-6583-72c8-ae9c-bec0dd89d193`
32 hex digits	`01a1d666658372c8ae9cbec0dd89d193`
Base64 (RFC byte order)	`AaHWZmWDcsiunL7A3YnRkw==`
128-bit integer (decimal)	`2169536338353678359565747661623120275`
.NET Guid.ToByteArray() (hex)	`66d6a1018365c872ae9cbec0dd89d193`
.NET Guid bytes (Base64)	`ZtahAYNlyHKunL7A3YnRkw==`

Standard (lowercase)

01a1d666-6583-72c8-ae9c-bec0dd89d193

Uppercase

01A1D666-6583-72C8-AE9C-BEC0DD89D193

Microsoft GUID (braces)

{01A1D666-6583-72C8-AE9C-BEC0DD89D193}

URN

urn:uuid:01a1d666-6583-72c8-ae9c-bec0dd89d193

32 hex digits

01a1d666658372c8ae9cbec0dd89d193

Base64 (RFC byte order)

AaHWZmWDcsiunL7A3YnRkw==

128-bit integer (decimal)

2169536338353678359565747661623120275

.NET Guid.ToByteArray() (hex)

66d6a1018365c872ae9cbec0dd89d193

.NET Guid bytes (Base64)

ZtahAYNlyHKunL7A3YnRkw==

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 01a1d666-6583-72c8-ae9c-bec0dd89d193 Copy

Formats

How to decode a UUID

Variant digit

Valid `01a1d666-6583-72c8-ae9c-bec0dd89d193`