FileGizmo Developer tools
Generate version 4 UUIDs
Generate random version 4 UUIDs in bulk, produced by your browser's cryptographic random source.
Simple by design
UUID generator in three steps
A UUID is a 128-bit identifier written as thirty-two hexadecimal digits in five groups. Version 4 fills almost all of those bits with random data, reserving a handful to record that the value is a version 4 UUID. The point is that anyone can create one without asking a central service, and it will still not clash with anyone else’s.
That property is what makes them useful for database keys generated on several machines, correlation identifiers threaded through logs, idempotency keys on an API, and filenames that must not collide. Because the value carries no meaning, it also leaks nothing: unlike a sequential key, a UUID does not reveal how many records exist or when one was created.
These are generated by the browser’s cryptographic random source rather than by a general purpose random function. That distinction matters whenever an identifier is used as anything resembling a secret, such as an unguessable link, because an ordinary random number generator can be predicted from earlier outputs.
Up to 500 can be produced at once, which covers seed data and fixture files without turning the page into a bulk data service. Nothing is recorded: close the tab and the list is gone.
- 1
Choose how many identifiers you need
- 2
Generate the list
- 3
Copy them into your database seed or configuration
Good to know
Frequently asked questions
Are these random enough to use in production?
They come from the browser's cryptographic random source, the same one used for encryption keys, rather than from an ordinary random number function.
What does version 4 mean?
Version 4 UUIDs are made almost entirely from random bits, with a few reserved to mark the version and variant. Other versions encode a timestamp or a hardware address instead.
Could two people generate the same one?
The space is large enough that a collision is not a practical concern. Generating a billion per second for a century still leaves the odds negligible.
Is the list stored or logged?
No. The identifiers are produced in the page and are gone when the tab closes, so nothing here keeps a record of what was generated.
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