UUID Validator & Decoder

Paste a UUID (also called a GUID) to check whether it is well-formed and to decode everything it encodes: its version, its variant, and — for the time-based versions — the exact moment it was created. Enter one UUID per line to validate a whole list at once.

What it checks

A canonical UUID is 32 hexadecimal digits shown in five dash-separated groups, 8-4-4-4-12, for example 550e8400-e29b-41d4-a716-446655440000. This tool first confirms that shape (upper- or lower-case hex, correct dashes). Anything that fails the pattern is reported as invalid, with a note explaining why.

For a valid UUID it then reads the two fixed metadata fields defined by RFC 4122 and RFC 9562:

• Version — the high nibble of the 7th byte. Versions 1 through 8 are recognised: v1 (time + MAC), v2 (DCE security), v3 (MD5 name-based), v4 (random), v5 (SHA-1 name-based), v6 (reordered time), v7 (Unix-time + random) and v8 (custom).
• Variant — the high bits of the 9th byte, which distinguish RFC 4122/9562 UUIDs from the older NCS and Microsoft layouts.

Decoding the embedded timestamp

Three versions carry a creation time, and the tool extracts and formats each one:

• v1 and v6 store a 60-bit count of 100-nanosecond intervals since the Gregorian reform date of 15 October 1582. The tool reassembles those bits (v6 stores them in sortable big-endian order), subtracts the 12,219,292,800,000 ms offset to the Unix epoch, and shows the result as an ISO 8601 timestamp. It also decodes the clock sequence and the node ID / MAC address, flagging whether the multicast bit marks it as a random rather than a hardware node.
• v7 stores a plain 48-bit Unix-millisecond timestamp in its leading bytes, so its creation time reads directly.

The nil UUID (00000000-0000-0000-0000-000000000000) and the max UUID (ffffffff-ffff-ffff-ffff-ffffffffffff) are recognised as their special reserved values.

Batch mode

Enter several UUIDs, one per line, and the summary tallies how many are valid. A batch table lists each entry with its validity, version and a short note, while the detailed decode is shown for the first UUID. Every table can be copied or downloaded as CSV.

Can this reveal the data inside a v3 or v5 UUID?

No. Versions 3 and 5 are one-way MD5/SHA-1 hashes of a namespace and a name. The tool identifies the hash algorithm, but the original inputs cannot be recovered from the digest.

Is anything uploaded?

No. Validation and decoding run entirely in your browser — the UUIDs you paste never leave your device.