How to use
- Select Generate UUID.
- Select Generate UUID again whenever you need a new value.
- Use Copy UUID to copy it to your clipboard.
How UUIDs are generated
Each UUID is created by your browser's Web Crypto API (crypto.randomUUID), which draws 122 random bits from the browser's cryptographically secure random number generator. The remaining 6 bits mark the value as a version 4, RFC 9562 (formerly RFC 4122) UUID.
UUIDs are written in lowercase hexadecimal, as 36 characters in five groups: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where y is 8, 9, a or b.
When to use a UUID v4
Version 4 UUIDs are random identifiers for database keys, request IDs, file names and test data. With 122 random bits, accidental collisions are extremely unlikely.
A UUID is an identifier, not a secret: it is not designed to be a password, an API key or a session token, and it should not be used as one.
Browser support
crypto.randomUUID is available in current versions of all major browsers on pages served over HTTPS. If it is not available, the tool shows an error instead of generating UUIDs from a weaker random source.
FAQ
- Are the UUIDs sent to a server or stored?
- No. UUIDs are generated in your browser. They are not sent anywhere, not stored, and not added to the page URL.
- Can two generated UUIDs be the same?
- In theory yes, but with 122 random bits the probability is so small that it can be ignored for practical purposes.