Productivity and Utilities

UUID Generator

Make random version 4 UUIDs in bulk, copy them in the format you need, and check the version and variant of one you already have.

How many (1 to 100)

Uppercase No hyphens Wrap in braces

These are version 4 UUIDs. A version 4 UUID has 122 random bits (6 of its 128 bits are fixed to mark the version and variant). That makes a repeat overwhelmingly unlikely, but it is not a guarantee of uniqueness, and a UUID is an identifier, not a secret. Do not use one as a password or security token unless you understand how it will be used. Everything runs in your browser and nothing is uploaded.

Check a UUID

Paste a UUID with or without hyphens, in braces, or with a urn:uuid: prefix. The check reads the version digit and the variant bits. It cannot tell whether the value was really generated by the method its version claims.

Next step

Password GeneratorMake a strong secret when you need a token or password, not just an identifier.
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How to use the uuid generator

Enter how many UUIDs you want, from 1 to 100, and press Generate.
Choose the format: Uppercase, No hyphens or Wrap in braces. The list changes at once without making new values.
Press Copy beside one UUID, or Copy all to copy the whole list with one UUID per line.
To inspect a UUID you already have, paste it into Check a UUID. The tool shows its normalized form, version and variant.

What a version 4 UUID is

A UUID is a 128 bit label written as 32 hexadecimal digits in groups of 8, 4, 4, 4 and 12. In a version 4 UUID, 6 of those bits are fixed: four bits hold the version number 4 and two bits mark the variant. The other 122 bits are random. That is why the third group always starts with 4 and the fourth group starts with 8, 9, a or b.

The tool asks the browser for the UUIDs through its secure random source. If the newer built-in function is missing, it fills 16 random bytes itself and sets the version and variant bits the same way. It never uses the weaker general purpose random function.

What a UUID does and does not promise

With 122 random bits, two generated values colliding is overwhelmingly unlikely for any realistic number of records, but nothing in the format forbids it. Treat a UUID as a very good identifier, and keep a unique constraint in your database if a duplicate would cause harm.

A UUID is also not a secret. It can appear in logs and URLs, and its randomness does not make it a safe password, session token or API key. Use it for IDs of rows, files and requests. If you need a token that grants access, design that on purpose with a proper security library, or use the password generator for a strong secret.

Reading version and variant bits

The checker reads the first digit of the third group as the version and the first digit of the fourth group as the variant. For example, the UUID f81d4fae-7dec-11d0-a765-00a0c91e6bf6 has the digit 1 in the version position, so it is a version 1 (time based) value, and its variant digit a is 1010 in binary, which starts with 10 and means the RFC 4122 layout that current UUIDs use.

The checker can only read the layout. It cannot prove that a value was produced by the method its version digit claims, and it does not look inside time based values. The nil UUID (all zeros) and the max UUID (all ones) are recognized as special cases. For other encodings of data see the Base64 encoder and decoder.

Formats and privacy

Uppercase, no hyphens and braces change only how the same 128 bits are written. Some systems print GUIDs in braces, and some databases store the 32 digits without hyphens. Everything runs in your browser and the UUIDs are never sent anywhere.

Assumptions and limits

Only version 4 (random) UUIDs are generated. Other versions can be checked but not made.
The count is limited to 1 to 100 per press so the page stays responsive.
Uniqueness is probabilistic. The tool does not check generated values against any list of values you already use.
Pasted UUIDs are read as hexadecimal digits, ignoring case. Braces and a urn:uuid: prefix are accepted.

Formulas reviewed October 10, 2026. See the calculation methodology for how SumPanda rounds, tests and sources its formulas.

Frequently asked questions

Is a UUID generated here guaranteed to be unique?

No format can guarantee that. A version 4 UUID has 122 random bits, so a repeat is overwhelmingly unlikely, but you should still enforce uniqueness in your own database when a duplicate would matter.

Can I use a UUID as a password or access token?

It is better not to. A UUID is an identifier that often shows up in URLs and logs. Unless you understand how the token will be stored and checked, use a purpose built secret from the password generator or a security library.

What do the 4 and the 8, 9, a or b in a UUID mean?

The 4 is the version digit, marking a random UUID. The digit at the start of the fourth group is 8, 9, a or b because its first two bits are the variant marker 10, which is the layout defined for current UUIDs.

Is a GUID the same as a UUID?

In practice yes. GUID is the name Microsoft uses, and it is usually written in braces and sometimes in uppercase. The Wrap in braces and Uppercase options produce that look from the same 128 bits.