About UUID Generator
Generate UUIDs in bulk using your browser cryptographic random number generator. Nothing is fetched from a server, so the values are yours alone and are never logged anywhere.
v4 or v7?
v4 is 122 random bits with no structure - the safe default when an identifier should reveal nothing. v7 puts a millisecond timestamp in the leading bits so ids sort chronologically as plain strings, which keeps database index inserts local instead of scattering them across the index. Choose v7 for primary keys on large tables, v4 when the id is public and should leak nothing about when it was created.
Formatting options
Uppercase and brace-wrapped forms show up in Microsoft tooling and registry keys; the hyphen-free form is common in URLs and database columns stored as 32 characters. All are the same 128 bits, so any of them can be parsed back.
Frequently asked questions
- Are these UUIDs safe to use as secrets?
- v4 UUIDs come from a cryptographic random source, but they are only 122 bits and are frequently logged, so treat them as identifiers, not as passwords or session tokens.
- How likely is a collision?
- For v4, negligible: generating a billion per second for around 85 years gives roughly a one in a billion chance of a single duplicate.
- Does a v7 UUID leak information?
- It embeds its creation time to the millisecond, which is readable by anyone holding the id. That is usually harmless for internal keys, and a reason to prefer v4 for anything public.