UUID Validator & Decoder: Version, Variant, Timestamp

Valid 01a1cfdd-3fd3-73d5-adff-29b73d7ab861

Version 7 Unix Epoch time-based Sortable by time

01a1cfdd3fd3 unix_ts_ms

7 ver

3d5 rand_a

adff29b73d7ab861 var + rand_b

Version	7 Unix Epoch time-based
Variant	RFC 9562 (formerly RFC 4122 / DCE 1.1) (bits `10`)
Timestamp (UTC)	`2026-11-12T13:05:45.939Z` Unix: 1794488745939 ms. Milliseconds.

Version

7 Unix Epoch time-based

Variant

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

Timestamp (UTC)

2026-11-12T13:05:45.939Z
Unix: 1794488745939 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)	`01a1cfdd-3fd3-73d5-adff-29b73d7ab861`
Uppercase	`01A1CFDD-3FD3-73D5-ADFF-29B73D7AB861`
Microsoft GUID (braces)	`{01A1CFDD-3FD3-73D5-ADFF-29B73D7AB861}`
URN	`urn:uuid:01a1cfdd-3fd3-73d5-adff-29b73d7ab861`
32 hex digits	`01a1cfdd3fd373d5adff29b73d7ab861`
Base64 (RFC byte order)	`AaHP3T/Tc9Wt/ym3PXq4YQ==`
128-bit integer (decimal)	`2169403777974080649816811772982245473`
.NET Guid.ToByteArray() (hex)	`ddcfa101d33fd573adff29b73d7ab861`
.NET Guid bytes (Base64)	`3c+hAdM/1XOt/ym3PXq4YQ==`

Standard (lowercase)

01a1cfdd-3fd3-73d5-adff-29b73d7ab861

Uppercase

01A1CFDD-3FD3-73D5-ADFF-29B73D7AB861

Microsoft GUID (braces)

{01A1CFDD-3FD3-73D5-ADFF-29B73D7AB861}

URN

urn:uuid:01a1cfdd-3fd3-73d5-adff-29b73d7ab861

32 hex digits

01a1cfdd3fd373d5adff29b73d7ab861

Base64 (RFC byte order)

AaHP3T/Tc9Wt/ym3PXq4YQ==

128-bit integer (decimal)

2169403777974080649816811772982245473

.NET Guid.ToByteArray() (hex)

ddcfa101d33fd573adff29b73d7ab861

.NET Guid bytes (Base64)

3c+hAdM/1XOt/ym3PXq4YQ==

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 01a1cfdd-3fd3-73d5-adff-29b73d7ab861 Copy

Formats

How to decode a UUID

Variant digit

Valid `01a1cfdd-3fd3-73d5-adff-29b73d7ab861`