UUID Generator
Generate v4 UUIDs in bulk, one click.
About this tool
Generate version 4 UUIDs — 128-bit identifiers built from random bytes — one at a time or in bulk. Handy for seeding test data, stubbing a fixture, or filling an ID column by hand.
They are produced with the browser's cryptographic random number generator, locally, so the values are never transmitted or recorded anywhere.
Common questions
Can two UUIDs collide?
In theory yes, in practice no. A v4 UUID has 122 random bits; you would need to generate billions per second for decades before a collision became likely. Every real-world duplicate traces back to a broken random source, not to chance.
Should I use a UUID as a database primary key?
It depends on the index. Random v4 values scatter inserts across a B-tree and fragment it, which is why high-write tables often prefer a sequential ID or a time-ordered format like UUIDv7. For most applications the difference is not measurable.
What is the difference between UUID v4 and v7?
v4 is entirely random. v7 puts a millisecond timestamp in the high bits, so values sort chronologically and index far better on insert, while keeping enough randomness to stay unguessable.
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