UUID Validator & Decoder: Version, Variant, Timestamp

Valid 01a1dfa5-5b3d-731b-8073-c04613fc8ae0

Version 7 Unix Epoch time-based Sortable by time

01a1dfa55b3d unix_ts_ms

7 ver

31b rand_a

8073c04613fc8ae0 var + rand_b

Version	7 Unix Epoch time-based
Variant	RFC 9562 (formerly RFC 4122 / DCE 1.1) (bits `10`)
Timestamp (UTC)	`2026-11-15T14:38:38.397Z` Unix: 1794753518397 ms. Milliseconds.

Version

7 Unix Epoch time-based

Variant

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

Timestamp (UTC)

2026-11-15T14:38:38.397Z
Unix: 1794753518397 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)	`01a1dfa5-5b3d-731b-8073-c04613fc8ae0`
Uppercase	`01A1DFA5-5B3D-731B-8073-C04613FC8AE0`
Microsoft GUID (braces)	`{01A1DFA5-5B3D-731B-8073-C04613FC8AE0}`
URN	`urn:uuid:01a1dfa5-5b3d-731b-8073-c04613fc8ae0`
32 hex digits	`01a1dfa55b3d731b8073c04613fc8ae0`
Base64 (RFC byte order)	`AaHfpVs9cxuAc8BGE/yK4A==`
128-bit integer (decimal)	`2169723868234876245419926840435051232`
.NET Guid.ToByteArray() (hex)	`a5dfa1013d5b1b738073c04613fc8ae0`
.NET Guid bytes (Base64)	`pd+hAT1bG3OAc8BGE/yK4A==`

Standard (lowercase)

01a1dfa5-5b3d-731b-8073-c04613fc8ae0

Uppercase

01A1DFA5-5B3D-731B-8073-C04613FC8AE0

Microsoft GUID (braces)

{01A1DFA5-5B3D-731B-8073-C04613FC8AE0}

URN

urn:uuid:01a1dfa5-5b3d-731b-8073-c04613fc8ae0

32 hex digits

01a1dfa55b3d731b8073c04613fc8ae0

Base64 (RFC byte order)

AaHfpVs9cxuAc8BGE/yK4A==

128-bit integer (decimal)

2169723868234876245419926840435051232

.NET Guid.ToByteArray() (hex)

a5dfa1013d5b1b738073c04613fc8ae0

.NET Guid bytes (Base64)

pd+hAT1bG3OAc8BGE/yK4A==

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 01a1dfa5-5b3d-731b-8073-c04613fc8ae0 Copy

Formats

How to decode a UUID

Variant digit

Valid `01a1dfa5-5b3d-731b-8073-c04613fc8ae0`