UUID / uuid-generator
UUID v4 generator
122 random bits, RFC 4122 layout.
- Sourcecrypto.getRandomValues()
- Entropy—
- draws112
A v4 UUID holds 128 bits, 122 of them random: six are fixed for version and variant. The layout is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where 4 marks the version and y is limited to 8, 9, a or b. Respecting those bits is not cosmetic: RFC 4122 parsers reject malformed UUIDs.
With 122 random bits the collision probability stays negligible for any real application: about 2.7 × 10^18 identifiers are needed for a 50% collision chance, per the birthday bound. It is not a counter, it is a coordinate in space.
How it works
- 01Choose how many UUIDs to generate, from one to one hundred.
- 02Toggle hyphens and uppercase to match the format your system expects.
- 03Copy everything at once: output is one UUID per line, ready to import.
Frequently asked
UUID v4 generator
UUID v4 or auto-increment?
It depends. Auto-increment is compact and ordered but leaks volume and requires coordination across nodes. UUID v4 needs no coordination and is opaque, but costs 16 bytes and fragments indexes. For high-volume primary keys, UUID v7 (time-ordered) is often the better call.
Are generated UUIDs globally unique?
Unique with overwhelming probability, not by guarantee. The randomness is cryptographic and the space is enormous, but absolute uniqueness does not exist in any distributed identifier scheme.
Can I use a UUID as a security token?
Yes, 122 random bits are adequate as an opaque token. Make sure the channel is encrypted and the token expires: the strength of the value does not compensate for an insecure transport.