UUID Decoder
Paste a UUID to see which version it is, whether it follows the standard and, for time-based versions, when it was made.
Decoding…
What the decoder can tell you
Every UUID has two small fixed parts: a version digit, which says how it was made, and a variant digit, which says which layout it follows. The decoder reads both, then reads whatever else that version stores.
- Any UUID: its version, its variant, and whether it follows RFC 9562.
- v1, v6 and v7: the date and time it was made, in UTC and in your own time zone.
- v1 and v6: the clock sequence and the node, and whether the node looks like a real network card address.
- ULID: the time in its first 10 characters.
It accepts the forms people paste most: with or without hyphens, in braces, as a urn:uuid:URN, in either case, or as Base64.
Which UUIDs have a time in them?
| Version | Has a time | Precision | Counts from |
|---|---|---|---|
| v1 | Yes | 100 ns | 15 Oct 1582 |
| v6 | Yes | 100 ns | 15 Oct 1582 |
| v7 | Yes | 1 ms | 1 Jan 1970 (Unix time) |
| ULID | Yes | 1 ms | 1 Jan 1970 (Unix time) |
| v3, v4, v5, v8 | No | None | None |
Questions people ask
Can I find out when a UUID v4 was made?
No. A UUID v4 is random apart from 6 bits, so it holds no time at all. Only v1, v6 and v7 carry a timestamp. A ULID does too.
Can the decoder tell which computer made a UUID?
Only for v1 and v6, and only if the generator used a real network card address as the node. Most modern libraries use a random node instead, and the decoder says which kind it found.
How accurate is the time?
v7 stores milliseconds. v1 and v6 store 100-nanosecond steps, which the decoder rounds down to the millisecond. Either way the time is only as right as the clock of the machine that made the ID.
What does "variant" mean?
Two bits after the third hyphen say which UUID layout is used. Almost every UUID today uses the RFC 9562 layout, shown by an 8, 9, a or b in that spot. Old Microsoft and NCS layouts exist but are rare.