Generate random version-4 UUIDs on demand — one or many, with or without hyphens, upper or lower case.
Generate up to 100 at once.
A UUID (universally unique identifier) is a 128-bit value written as 32 hexadecimal digits, usually split into five hyphen-separated groups. Version 4 fills those bits with random data — apart from a few reserved for the version and variant — so two independently generated values practically never collide. That property makes UUIDs handy as database keys, request IDs, and file names when you need uniqueness without a central counter.
Leave the defaults and you get one lowercase, hyphenated v4 UUID such as 3f2504e0-4f89-41d3-9a0c-0305e82c3301. The single “4” in the third group marks the version; the first digit of the fourth group is always 8, 9, a, or b.
Set the count to 25 to seed a test fixture in one click — each line is an independent identifier you can paste straight into a database or mock payload.
Turn off hyphens for a compact 32-character form (like 3f2504e04f8941d39a0c0305e82c3301) that fits neatly into URLs, object keys, or filenames where dashes are awkward.
How unique is a version-4 UUID really?
A v4 UUID has 122 random bits. You would need to generate on the order of a billion UUIDs per second for about 85 years to reach a 50% chance of a single collision, so for ordinary application use they are effectively unique.
What is the difference between a UUID and a GUID?
They are the same thing. GUID (globally unique identifier) is Microsoft’s name for the format; UUID is the term used by the RFC 4122 standard. The bytes and layout are identical.
Should I use UUIDs as database primary keys?
You can — they let clients create keys without a round trip and avoid guessable sequential IDs. The trade-off is size and index locality; random v4 keys scatter across an index, which is why some teams prefer time-ordered schemes for very large, write-heavy tables.
Is this generator random enough to trust?
Yes. It uses the browser’s cryptographically secure Web Crypto API, not Math.random, and runs entirely on your device — nothing is requested from or sent to a server.