UUID/GUID Generator
Generate unique identifiers instantly
📋 Generated UUID(s)
About UUID Generator
A UUID is a 128-bit identifier written as 36 characters — 32 hexadecimal digits in five hyphen-separated groups. It is designed to be generated independently on any machine without a central authority and still be unique. This tool produces version 1 and version 4 UUIDs.
Version 1 versus version 4
Version 1 derives from a timestamp and the generating machine's identity, so v1 values sort roughly in creation order but leak when and where they were made. Version 4 is almost entirely random — 122 of its 128 bits — carrying no information about origin or time. Version 4 is the sensible default; choose version 1 only when time-ordering genuinely helps, such as clustering rows in an index.
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx the digit before the third group is the version — a 4 marks a random UUID — and y encodes the variant.Can two UUIDs ever collide?
In theory yes, in practice no. With 122 random bits you would need to generate billions of UUIDs per second for a century before a collision became likely. The realistic risk is not mathematics but a faulty random source — which is why generation should use a cryptographic random generator, as your browser's does.
Should I use a UUID as a database primary key?
It works, but consider the cost. UUIDs are 16 bytes against 4 or 8 for an integer, and random v4 values scatter inserts across the index instead of appending to the end, which can fragment it. The gain is that clients can create IDs offline and systems can be merged without renumbering.
Try our other free tools: hash generator, base64 encoder, and password generator.