UUID Generator
Generate cryptographically random UUIDs in bulk. Supports version 4 and time-ordered version 7, with uppercase, braces and no-hyphen formats.
Related tools
All Developer tools →This tool runs entirely in your browser. Nothing you enter is sent to our servers, so there is nothing for us to store or see.
About the UUID Generator
A UUID is a 128-bit identifier that can be generated independently on any machine with a negligible chance of ever colliding. That property is what makes them useful: you can create a primary key on a client, offline, without asking a central database to allocate one.
Version 4 UUIDs are entirely random and are the right default for most uses. Version 7 encodes a Unix timestamp in its leading bits, which makes a series of them sort chronologically — a real advantage as a database primary key, because random v4 keys scatter inserts across a B-tree index and fragment it, while v7 keys append in order.
Randomness comes from the Web Crypto API, the same cryptographically secure source your browser uses for TLS — not from Math.random, which is predictable and unsuitable for identifiers that must not be guessable.
How to use the UUID Generator
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Choose a version
Version 4 for general use. Version 7 when the identifiers will be database keys and you want them to sort by creation time.
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Choose how many
Generate a single UUID or up to a thousand at once for seeding test data.
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Pick a format
Standard lowercase with hyphens is the norm. Uppercase, braces and hyphen-free variants are available for systems that expect them.
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Copy or download
Copy puts the whole list on your clipboard. Download saves it as a text file, one per line.
Frequently asked questions
Are these UUIDs truly random and safe to use?
Yes. They are generated with the Web Crypto API, which is your browser cryptographically secure random source — the same one used for TLS key material. This tool never uses Math.random, which is predictable and would make identifiers guessable.
What is the difference between UUID v4 and v7?
Version 4 is 122 bits of pure randomness. Version 7 replaces the leading 48 bits with a millisecond Unix timestamp, so UUIDs generated later always sort after earlier ones. Version 7 is generally better as a database primary key because sequential inserts keep the index compact, while random v4 keys fragment it.
Could two UUIDs ever be the same?
In theory yes, in practice no. A version 4 UUID has 122 random bits, giving about 5.3 undecillion possibilities. You would need to generate roughly a billion UUIDs per second for 85 years to reach a 50 percent chance of a single collision.
Are these generated on your server?
No. Generation happens entirely in your browser. Nothing is transmitted, logged or stored, so the identifiers you create here exist only on your device until you use them somewhere.
Is a UUID the same thing as a GUID?
Effectively yes. GUID is Microsoft naming for the same 128-bit identifier standard. The main difference you will encounter is formatting convention: Microsoft tooling often shows them in uppercase wrapped in braces, which is available here as a format option.