Decode a UUID you found in a log or URL

That 36-character string encodes a version, sometimes a timestamp, sometimes a MAC. Here is how to read what kind of identifier you are holding.

Tools used in this guide

The job

A UUID in a URL or log line is not random noise — the format tells you which UUID version generated it, and time-based versions leak the moment they were minted. That matters when correlating events or checking ID guessability.

Inspect it

Paste the UUID — hyphens, braces, and the urn:uuid: prefix are all accepted. The tool reports the version (1, 3, 4, 5, 6, 7, or nil/max specials), the variant, and for v1/v6/v7 the embedded timestamp as ISO time plus clock-seq and node fields where they exist.

Worked example

550e8400-e29b-41d4-a716-446655440000 reads as version 4, RFC 4122 variant — a random ID with no embedded data. 6ba7b810-9dad-11d1-80b4-00c04fd430c8 is version 1 with a 1998-02-04 timestamp and a node field — generated when it was minted, not now.

v4 = random, most common in APIs.
v1/v6 = timestamp + node (often a MAC-derived value).
v7 = Unix-ms timestamp — sortable, the modern default for database keys.

Limits

The node field is shown as hex, not resolved to hardware — most modern v1 generators use a random multicast node anyway. Non-RFC variants and nil/max UUIDs are flagged rather than decoded as if they were normal.