Generate version 4 UUIDs locally in your browser using crypto.randomUUID()
(with a fallback for older browsers). Choose how many UUIDs to create (1–500) and whether hexadecimal letters appear in lowercase (common in APIs and logs) or uppercase. Nothing is sent to the server.
A version 4 UUID is a 128-bit identifier whose non-version bits are generated from cryptographically secure random bytes. It does not require a central counter or database, which makes it convenient for client-generated IDs, test records, fixtures, filenames, distributed services, and import jobs.
Lowercase and uppercase values represent the same UUID; letter case only changes display. UUID v4 values do not contain a creation time and do not sort by age. Use UUID v7 Generator when roughly time-ordered identifiers are more useful for a database index or event stream.
Random UUID collisions are extremely unlikely, but applications should still enforce uniqueness where duplicates would be harmful. Treat UUIDs as identifiers rather than secrets: they are not passwords, access tokens, or proof of authorization.