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TinyTools

UUID Generator

Cryptographically random identifiers, made in your browser.

max 1000

Everything is processed on your device. Nothing you upload or type is sent to a server, and nothing is stored.

UUID Generator online

A UUID is a 128-bit identifier you can create without asking anyone — no central counter, no database round trip, no coordination between services — and still be confident nobody else will ever generate the same one. Version 4 gets that from pure randomness, which is why the random source matters: these come from your browser's cryptographic generator, not from Math.random.

How to use uuid generator

  1. Choose how many

    One, or up to a thousand at a time for seeding a database.

  2. Set the format

    Hyphens on or off, uppercase or lowercase, to match whatever you are pasting into.

  3. Copy or download

    Take the whole list to your clipboard, or save it as a text file.

Frequently asked questions

Are these really unique?

Effectively, yes. A v4 UUID has 122 random bits, so you would need to generate about 2.7 × 10¹⁸ of them before a collision became likely — roughly a billion a second for 85 years. In practice UUIDs fail because someone reuses one, never because two were generated the same.

Is it safe to generate them in a browser?

Yes. These use crypto.randomUUID or crypto.getRandomValues, the same cryptographically secure source used for keys and tokens, and it never touches Math.random — which is fast, predictable, and completely unsuitable for identifiers.

What is the difference between a UUID and a GUID?

Nothing that matters. GUID is Microsoft's name for the same 128-bit identifier and the same format; the two terms are interchangeable in every context you are likely to meet. Some Microsoft tooling prints them in uppercase and wrapped in braces, which is a display convention rather than a different thing.

Should I use a UUID as a database primary key?

It is a real trade-off. UUIDs let you create rows without a round trip and merge data between systems safely, but v4 is random, so inserts land all over the index and fragment it. If that bites, look at UUID v7, which puts a timestamp at the front so new keys sort together.

Why do all of these have a 4 in the same place?

That digit is the version field, and it is always 4 for a randomly generated UUID. The character after the third hyphen is the variant, which is why every one of these starts that group with 8, 9, a or b. Both are fixed by the specification, leaving 122 of the 128 bits free.

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