UUID Generator and Decoder
Generate UUIDs or paste existing IDs to inspect versions, variant, duplicates, and v1 time data.
UUID Generator and Decoder
Generate UUIDs or paste existing IDs to inspect versions, variant, duplicates, and v1 time data.
About UUID generation and decoding
Choose the right UUID version
Versions 1 and 4 can generate batches without a name. Versions 3 and 5 derive one deterministic UUID from a name and namespace; the same input gives the same result. Use a built-in DNS or URL namespace, or provide a valid custom namespace UUID.
Local output for copy or download
The identifiers are created in your browser and returned as newline-separated text for quick copying or download. Version 3 uses MD5 and version 5 uses SHA-1 as UUID namespace algorithms, so treat them as identifier formats rather than password or signature hashing recommendations.
Decode a list and inspect each structure
Switch to Decode and paste one UUID per line, up to 1,000 at a time. Hyphenated UUIDs and 32 hexadecimal characters are accepted, in either case. Select a line to inspect its version and variant; v1 also exposes its timestamp, clock sequence, and node. The list flags invalid formats and repeated UUIDs, and the JSON report retains these results.
FAQ
Common questions and answers about this topic.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify information in computer systems without requiring central coordination.
What UUID versions are supported?
Generation supports v1 (time), v3 (MD5 with a name and namespace), v4 (random), and v5 (SHA-1 with a name and namespace). v1 and v4 support batches; v3 and v5 produce one ID per operation. Decoding identifies version and variant, but v2 and v6–v8 are only recognized by version number; their version-specific fields are not decoded.
Are generated UUIDs truly unique?
UUID v4 has 122 random bits, so collisions are very unlikely but not impossible. v3 and v5 deliberately return the same UUID for the same name and namespace. The decoder flags repeated UUIDs in the pasted list; this does not prove uniqueness across other databases or services.
Is my data sent to any server?
No. UUID generation and decoding run locally in your browser. Pasted IDs and decoded fields are not sent to a server, and JSON reports are created locally for download.
How do I decode a UUID list?
Choose Decode, paste one UUID per line, and select a line to inspect the structure. Up to 1,000 nonempty lines are accepted. Format errors and repeated IDs are marked next to the lines, and you can download the results as a JSON report.
Can a UUID reveal its creation time or original name?
For RFC variant v1 UUIDs, the tool decodes the embedded timestamp, clock sequence, and node. The node does not identify a specific machine. v3 and v5 contain hashes, so the original name and namespace cannot be recovered; v4 has no creation timestamp. v2 and v6–v8 are only recognized by version number here, without decoding their specific meaning.