UUID Decoder

Field	Value	Copy
{{ row.label }}	{{ row.value }}

Segment	Hex	Binary	Detail	Copy
{{ segment.label }}	{{ segment.hex }}	{{ segment.binary }}	{{ segment.detail }}

Five UUID segments with a small clock overlay.

Universally Unique Identifiers are 128 bit labels used to tag records and events across distributed systems. A clear UUID version and variant decoder helps you understand what kind of identifier you have.

A decoded identifier shows its version and variant, whether a timestamp is present, and where ordering likely comes from. You also see the node indicator and the clock sequence when those fields exist.

You paste a value and choose how timestamps display, then read structured fields and a compact bit layout that maps each group to meaning. Copy a short summary when you need to share a finding.

Imagine checking a version seven value from a log where the first six bytes carry a millisecond time and the rest provide randomness. You confirm the moment and keep a preferred representation for notes.

Treat structural passes with care. A valid pattern does not prove an active account or a real network address and many generators randomize the node bytes.

Technical Details:

A Universally Unique Identifier (UUID) is a 128‑bit value composed of time fields, a version nibble, variant bits, a clock sequence, and a node segment. The decoder parses these parts, reports their meaning in human‑readable form, and mirrors the underlying bit layout.

For versions 1, 2, and 6, the timestamp is a 60‑bit count of 100‑nanosecond intervals since 1582‑10‑15. For version 7, the first 48 bits encode Unix time in milliseconds. Versions 3 and 5 are namespaced hashes, version 4 is random, and version 8 is reserved for custom layouts.

Results include canonical and alternate renderings, the detected variant family, any available time in multiple displays, the clock sequence, and node flags indicating locally administered or multicast addressing. Nil and Max values are recognized to support testing and boundary checks.

Comparisons are strongest within a single generator family. Time‑ordered layouts such as versions 6 and 7 can support range queries and log joins; purely random layouts such as version 4 cannot be sorted by creation time.

\begin{matrix} t_uuid & = & time_high \times 2^{48} + time_mid \times 2^{32} + time_low \\ t_ms & = & \frac{t_uuid - Δ}{10^{4}} \\ t_s & = \frac{t_uuid - Δ}{10^{7}} \\ t_ms (v7) & = & big‑endian integer of bytes 0–5 \end{matrix}

Symbols and units
Symbol	Meaning	Unit/Datatype	Source
t_uuid	UUID time count for versions 1, 2, 6	100‑ns ticks	Derived
Δ	Gregorian to Unix offset	0x01B21DD213814000 ticks	Constant
t_ms	Unix epoch time	Milliseconds	Derived
t_s	Unix epoch time	Seconds	Derived
bytes[0..5]	Version 7 timestamp segment	Octets	Input

Worked example (Version 1): Given f81d4fae-7dec-11d0-a765-00a0c91e6bf6, the version nibble is 1 and the variant byte 0xA7 matches pattern 10xx (RFC 4122). Extracted fields are time_low=0xf81d4fae, time_mid=0x7dec, time_hi_and_version=0x11d0 so time_high=0x01d0.

\begin{matrix} t_uuid & = & 0x1d07decf81d4fae \\ t_ms & = & \frac{0x1d07decf81d4fae - 0x01B21DD213814000}{10^{4}} = 854991792216.875 \\ t_s & = & 854991792.216875 \end{matrix}

Displayed as ISO 8601 UTC, the moment is 1997‑02‑03T17:43:12.216Z. Version 1 does not guarantee a real MAC address in the node field.

Validation & bounds extracted from code

Validation rules and limits
Field	Type	Min	Max	Step/Pattern	Error Text / Placeholder
UUID input	String	32 hex digits	32 hex digits	^[0-9a-fA-F]{32}$ after removing hyphens, spaces, optional urn:uuid: and outer braces	“UUIDs require exactly 32 hexadecimal digits (hyphens optional).” • Placeholder example 550e8400‑e29b‑41d4‑a716‑446655440000
Multiple lines	Textarea	1 line	—	Only the first non‑empty line is decoded; extra lines are ignored	Warning banner with dismiss control
Preferred representation	Select	—	—	canonical • uppercase • braced • urn • no dash	Affects summary badges and tables
Timestamp display	Select	—	—	UTC • Local • Unix seconds • Unix milliseconds	Sets the label and the value shown in fields

I/O formats & encoding

Input and output formats
Input	Accepted Families	Output	Encoding/Precision	Rounding
UUID string	Canonical, uppercase, brace‑wrapped, urn:uuid:…; hyphens optional	Fields table	Text values	—
—	—	Bit layout	Hex and binary; binary width = 4×hex digits	None
—	—	Structured JSON	Indented two spaces	Timestamps shown as ISO‑8601, Unix seconds, or Unix milliseconds
—	—	Optional CSV / DOCX exports	UTF‑8 text / Office document	Decimal separator is period

Networking & storage behavior

Processing occurs locally; no network requests are made during decoding.
Copy actions write to the clipboard; downloads create local files on demand.
No persistent storage is used; state resets when the page is refreshed.

Assumptions & limitations

Version detection relies only on the version nibble and does not validate namespace inputs for versions 3 or 5.
Version 4 quality is not assessed; randomness is not tested.
Node bytes may be random or synthesized; do not assume a real NIC address.
Version 2 POSIX data is not interpreted beyond timestamp handling.
Version 8 meaning is generator‑specific; fields are shown as opaque where appropriate.
Timestamps far outside the Unix epoch range can lose sub‑millisecond precision when converted to display formats.
Binary renderings reflect current endianness rules for each version; alternate proposals are not evaluated.
Heads‑up Structural validity does not prove an account, host, or record exists.

Edge cases & error sources

Non‑hex characters or length other than 32 after normalization cause a validation error.
Mismatched or partial braces are stripped only at the outermost positions.
Only the first non‑empty line is decoded; extra lines are ignored with a notice.
Exotic whitespace is removed if matched; unrecognized separators are rejected.
Dates near leap seconds show standard ISO behavior without leap‑second modeling.
Local time display reflects the device clock and timezone settings.
Very large timestamps can exceed safe integer ranges for some displays.
Version 2 and 8 generators vary; details may not map cleanly to named fields.
Variant identification is based solely on high‑order bits of the 9th byte.
Parsing assumes base‑16 digits only; Unicode look‑alikes are not accepted.

Scientific and standards backing

UUID structure and variants follow RFC 4122 conventions. Version 6 and version 7 handling reflects widely adopted community specifications for time‑ordered identifiers.

Privacy & compliance

No data is transmitted or stored server‑side. If identifiers are sensitive, prefer test values or masked samples in shared documents.

Step‑by‑Step Guide

UUID decoding with timestamp and structure reveal.

Paste a value into UUID.
If a timestamp exists, choose its display mode.
Pick a preferred representation to anchor copies and tables.
Review fields, variant, and node flags for quick context.
Open the Bit Layout tab to see hex and binary segments.
Copy, download, or export a summary when needed.

Example: Paste a version 7 value to see Unix milliseconds in UTC, Local, seconds, or milliseconds.

You now have a compact, shareable record of the identifier’s structure and timing.

FAQ

Is my data stored?

No. Decoding runs on your device and nothing is persisted or sent to a server.

Copy and download actions create local artifacts only.

Which versions are decoded?

Versions 1 through 8 are recognized. Timestamp extraction is available for versions 1, 2, 6, and 7.

Version 8 is shown as custom where semantics are generator‑specific.

How accurate is the timestamp?

Version 7 shows milliseconds. Versions 1, 2, and 6 derive time from 100‑ns ticks and are displayed as ISO and Unix values.

Display rounding follows standard time APIs.

What formats can I paste?

Canonical, uppercase, brace‑wrapped, and urn:uuid:… forms are accepted. Hyphens are optional.

Only the first non‑empty line is used.

Can I use it offline?

Yes. The decoder does not require a network connection once loaded.

Device time affects local timestamp displays.

What does a Nil UUID mean?

All bits are zero. It is commonly used as a sentinel or reset value.

It does not identify a real entity.

How do I inspect a GUID?

Paste the GUID. The variant row will indicate the Microsoft family when present and fields will decode as usual.

GUIDs and RFC 4122 UUIDs share the same 128‑bit layout with variant differences.

What does “borderline” result mean?

Values near time boundaries may look surprising in local time. Switch between UTC and Local to confirm the intended moment.

Troubleshooting

Validation error: remove spaces and punctuation other than hyphens.
Wrong variant: check the 9th byte; copy the Bit Layout row to verify.
No timestamp shown: versions 3, 4, 5, and many 8 layouts have none.
Odd local time: confirm device timezone and daylight saving settings.
Copy did nothing: allow clipboard access and try again.
CSV looks wrapped: open with a UTF‑8 aware editor or spreadsheet.

If you see “UUIDs require exactly 32 hexadecimal digits”, normalize the input by removing braces, the urn:uuid: prefix, hyphens, and spaces until only 32 hex digits remain.

Glossary

UUID: A 128‑bit identifier with version and variant fields.
Version: Encodes generation method such as time‑based, random, or namespaced.
Variant: Selects the interpretation family, including RFC 4122 and Microsoft GUID.
Clock sequence: Counter that helps uniqueness for rapid generation.
Node: A 48‑bit field that may reflect a MAC‑like value or randomness.
Nil / Max: All‑zero or all‑one patterns used for testing or sentinels.
Canonical: Lowercase with hyphens in 8‑4‑4‑4‑12 grouping.
URN: Uniform Resource Name form prefixed with urn:uuid:.