Generate version 4 or version 7 UUIDs in your browser, from your system’s cryptographic random source. Your file never leaves this page. Everything happens in your browser, and there is no upload endpoint to send it to — that is checked by a build gate that fails if any network code reaches a tool’s bundle.
How to do it
- Choose version 4 or version 7.
- Press Generate, or Generate 10 for a batch.
- Press Copy.
Questions
What is the difference between version 4 and version 7?
Version 4 is entirely random. Version 7 begins with a timestamp and fills the rest with randomness, so identifiers sort in the order they were created.
Which one should I use for a database key?
Version 7, usually. Because version 4 identifiers are random, inserting them into an index writes to a different page every time and the index fragments. Version 7 inserts land at the end, which keeps it tidy. Use version 4 when the identifier must reveal nothing at all — a version 7 UUID tells anyone holding it roughly when it was made.
Are these random enough to rely on?
Yes. They come from your system’s cryptographic random source, never from Math.random(), which is predictable and not suitable for identifiers.
Could two of these ever collide?
In practice, no. A version 4 UUID has 122 random bits; you would need to generate billions per second for decades before a collision became likely.