UUID Decoder
Paste a UUID to check whether it's valid, see its version and variant, and — for v1, v6 and v7 — the real timestamp encoded inside it. Runs entirely in your browser.
Need to generate a UUID instead of decode one? The UUID generator makes every version — v1 through v8, plus Nil and Max.
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Counted live by your browser's own Performance Timeline — the same data the DevTools Network panel reads. It cannot see what a browser extension does, and it is not meant to replace checking for yourself: here is how, in thirty seconds .
Is this UUID valid?
A UUID is valid, as a string, if it's 32 hex digits in the right layout — with or without
hyphens, braces or a urn:uuid: prefix. This page checks exactly that and says so
with a badge the moment it parses. That's a separate question from whether it's a
recognized version: an all-zero Nil UUID, an all-f Max UUID, or a UUID
using one of the older NCS/Microsoft variants are all valid strings with no v1-v8 "version" —
the version and variant badges say which case you've got.
What UUID version is this?
This tool never guesses from a UUID's shape — it reads the version nibble and variant bits exactly as RFC 9562 (the current spec, which obsoletes the older RFC 4122) defines them, and says plainly when those bits don't resolve to a known version (an NCS, Microsoft, or future-reserved variant UUID has no "version" in the v1-v8 sense).
How to decode a UUID by hand
Write the UUID as 32 hex digits in five hyphenated groups
(8-4-4-4-12). The 13th hex digit — the first digit of the third
group — is the version, 1 through 8. The 17th hex digit — the first digit of
the fourth group — carries the variant in its top bits: 10xx means RFC
9562/4122, the variant every version above actually uses. Once you know the variant is RFC
9562, the version digit tells you which of the eight generation schemes produced it, and for
v1, v6 and v7 the remaining bits unpack into a real timestamp — this page does that
arithmetic for you below.
Can you get the creation time from a UUID?
For v1, v6 and v7 — yes, exactly. They each embed a real creation timestamp — v1/v6 as 100-nanosecond ticks since 1582-10-15, v7 as milliseconds since 1970-01-01. This page extracts it and shows both the UTC instant and your browser's local time, with a direct link to the epoch converter for further conversion. For v3, v4, v5 and v8 — no. Those versions carry no timestamp at all; there's nothing to extract, and no amount of decoding recovers one that was never encoded.
Common use cases
- Checking whether a UUID a system gave you is actually the version you expect
- Finding out exactly when a v1/v6/v7-keyed record was created, from the ID alone
- Auditing whether a legacy v1 UUID is leaking a real MAC address
- Verifying a v5 UUID against a namespace+name guess, via the generator
Frequently asked questions
- Is my UUID sent to a server?
- No. Decoding happens entirely in your browser — the value you paste never leaves your device or gets logged anywhere.
- What's the difference between version and variant?
- The variant (the first bits of the 17th hex digit) says which layout rulebook the UUID follows — almost every UUID you'll ever see is the RFC 9562/4122 variant. The version (the first digit of the 13th hex digit) only means something once you know the variant is RFC 9562, and it says which of the eight generation schemes (v1-v8) produced it.
- Why does my UUID v1 leak my MAC address?
- RFC 9562 defines v1's last 48 bits as a "node id", and the traditional implementation fills it with the generating machine's real network MAC address. Every v1 UUID from that machine then shares that same value forever — a stable, extractable identifier, plus the precise creation timestamp this page decodes. If the node id below doesn't have its lowest bit set, that's the shape of a real MAC rather than a randomly generated one.
- Can a UUID v5 be reversed back to its namespace and name?
- No — v5 (and v3) are one-way hashes of a namespace UUID plus a name string. You cannot recover the original inputs from the UUID alone. If you have a guess at what they were, use the UUID generator's v5 mode to check it: generate that namespace+name combination and compare the result to what you pasted here.
- What's the difference between UUID and GUID?
- Nothing structurally — GUID is Microsoft's name for the same 128-bit layout this page decodes.