UUID Generator
Free UUID generator for v4 random, v7 time-ordered and nil UUIDs. Make up to 1,000 at once, pick the format and copy them, and validate any UUID.
How to use UUID Generator
- 1Pick a version (v4, v7 or nil) and how many UUIDs you need, up to 1,000.
- 2Choose the format: hyphens, uppercase, braces, quotes and one per line, comma separated or a JSON array.
- 3Copy or download the list, or press Regenerate for new ones.
What makes it better
- Version 4 random, version 7 time-ordered and the nil UUID
- Up to 1,000 UUIDs per batch
- Hyphens, UPPERCASE, {braces} and quotes toggles
- Output as lines, a comma list or a JSON array
- Built-in validator that reports version and variant
About UUID Generator
UUID Generator creates universally unique identifiers in your browser: random version 4, time-ordered version 7 as defined in RFC 9562, or the all-zero nil UUID. Choose hyphens, uppercase, braces or quotes, output them as lines, a comma list or a JSON array, and paste any UUID into the checker to see its version and variant.
Common uses
- Fill a test database or fixture file with unique primary keys.
- Use v7 identifiers that sort by creation time to keep database indexes friendly.
- Generate a JSON array of IDs to paste into an API request or mock data.
- Check whether an identifier from a log is a valid UUID and which version it is.
Example
Input
Version 4, hyphens, lowercase, one per line (sample only: every UUID you generate is new)
Result
3f2b8c1e-9d4a-4e7b-8a15-6c0d2f9b7e41
Good to know
- Version 4 UUIDs carry 122 random bits from the browser's cryptographic generator, so collisions are not a practical concern. A UUID is an identifier, not a secret, so do not use one as a password or access token.
- Version 7 puts the current Unix time in milliseconds in the first 48 bits and fills the rest randomly. Several UUIDs created in the same millisecond are not guaranteed to be in order, and they reveal roughly when they were made.
- The validator checks the format, version and variant bits only. It cannot tell whether a UUID is assigned to anything.
UUID Generator FAQ
What is the difference between UUID v4 and v7?
Version 4 is almost entirely random, while version 7 starts with a millisecond timestamp so new IDs sort after older ones. That ordering keeps B-tree database indexes more compact than fully random keys.
Can two generated UUIDs be the same?
In theory yes, in practice no: you would need to create billions of version 4 UUIDs per second for many years to expect a single collision. The odds depend entirely on the randomness source, which here is crypto.getRandomValues.
What is a nil UUID used for?
The nil UUID is 00000000-0000-0000-0000-000000000000, a reserved value that means no identifier. Developers use it as a placeholder or default in schemas and tests.
Are GUID and UUID the same thing?
Yes. GUID is Microsoft's name for the same 128-bit format, often written uppercase and wrapped in braces, which the Uppercase and Braces options reproduce.
How do I read a UUID's version?
The version is the first digit of the third group, so in 3f2b8c1e-9d4a-4e7b-8a15-6c0d2f9b7e41 it is 4. Paste a UUID into the checker and it also names the variant and shows the timestamp of a v7 UUID.