UUID Generator
Generate UUIDs and GUIDs in v4 (random) or v7 (time-ordered) format for databases and APIs, with bulk generation and one-click copy, free with no signup.
Ready to generate a UUID
Select a version and press Generate.
About this generator
A UUID (also called a GUID) is a 128-bit identifier for something that needs to be unique without a central system handing out sequential numbers: a database row, an API request, a session token, a file. This generator supports both of the versions that matter today, v4 and v7, and the difference between them is worth knowing before you pick one.
UUID v4 is fully random: 122 of its 128 bits come straight from a random source, so a collision is astronomically unlikely even generating billions per second for years. It's the default most systems reach for when uniqueness is all that's needed.
UUID v7 is newer and embeds a millisecond-precision timestamp in its leading bits, so values sort chronologically in the order they were created. That property makes v7 the better fit for database primary keys: sequential-ish values avoid the index fragmentation that fully random v4 keys cause in B-tree indexes, while still remaining effectively unique like v4.
The tradeoff is exposure: because v7 encodes creation time, it reveals roughly when a record was made if the ID ever surfaces publicly, something v4 never gives away. For internal keys that rarely matters; for public-facing identifiers where creation time should stay private, v4 is the safer pick.
Frequently Asked Questions
What's the actual difference between v4 and v7?
v4 is fully random with nothing embedded in it; v7 embeds a millisecond timestamp, so v7 values sort in the order they were generated while v4 values don't.
Are generated UUIDs guaranteed unique?
Not mathematically guaranteed, but close enough in practice: v4's 122 random bits make a collision astronomically unlikely even across billions of generations.
Which version fits a database primary key better?
v7, generally: its time-ordered structure avoids the index fragmentation that fully random v4 keys cause in B-tree indexes, without sacrificing uniqueness.
Does v7 leak when a record was created?
Yes. Its embedded timestamp reveals roughly when it was generated if exposed publicly; use v4 instead when creation time needs to stay private.
Can either version go in a public URL safely?
Both work fine in URLs and APIs; just remember v7's timestamp is technically recoverable, so reach for v4 if that timing detail shouldn't be exposed.
Are UUIDs and GUIDs the same thing?
Yes, GUID is Microsoft's name for the same 128-bit concept standardized as UUID; the terms are used interchangeably.