Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Generate random RFC 4122 version 4 UUIDs, one or many at a time.
Click Generate to create new UUIDs.
A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify records, sessions, or resources without needing a central coordinating authority. This tool generates random version 4 UUIDs -- the most common variant, where the identifier is derived entirely from random bits rather than a timestamp or hardware address.
Choose how many UUIDs to generate (1-100) and click Generate. Each UUID is unique and follows the standard 8-4-4-4-12 hexadecimal format.
The browser's crypto.randomUUID() (backed by the Web Crypto API's cryptographically strong random number generator) produces each UUID. Version 4 UUIDs fix specific bits to mark the version and variant, leaving 122 bits genuinely random -- with that much randomness, accidental collisions are astronomically unlikely.
For a general-purpose random alphanumeric string instead, see the Random String Generator.
A UUID is written as 32 hexadecimal digits in five groups separated by hyphens, in the pattern 8-4-4-4-12. In a version 4 UUID two positions are fixed and the rest are random. The first digit of the third group is always 4, which marks the version. The first digit of the fourth group is always 8, 9, a or b, which marks the variant defined by RFC 4122. Everything else, 122 bits in total, comes from a random source. That is why you will see identifiers like the shape xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where y is one of those four digits. You can use this pattern to sanity-check a value you were given: if the third group does not start with 4, it is not a version 4 UUID.
Random bits: 128 total - 4 (version) - 2 (variant) = 122 random bits.
The count field accepts a whole number from 1 to 100. Values below 1 are raised to 1 and values above 100 are capped at 100, and an empty or non-numeric entry falls back to 1. Each click of the generate button replaces the current list with a fresh batch, so copy or download what you need first. The list opens with five UUIDs on page load, and the clear action empties the output. The download option saves the batch as a plain text file with one UUID per line, which is convenient for seeding test fixtures or spreadsheets.
Imagine you are writing a database migration that inserts twelve sample rows and each row needs a primary key. Set the count to 12, generate, and copy the list. Each line is a separate ID, so you can paste them into a script or a spreadsheet column and pair them with your sample data. Because the values are random, you should save the list you used if you need the same identifiers again later; generating again produces entirely different ones.
In theory yes, but with 122 random bits, the probability is so vanishingly small (you'd need to generate roughly a billion UUIDs per second for about 85 years to have a 50% chance of one collision) that it's treated as effectively impossible in practice.
Yes -- GUID (Globally Unique Identifier) is Microsoft's name for the same concept defined by the UUID standard (RFC 4122); they're interchangeable in practice.
The 8-4-4-4-12 hyphenated format is fixed by the standard, and specific bit positions are fixed to mark "version 4" -- everything else is randomly generated, which is why the values differ each time.
Look at the first character of the third group: it is 4 for version 4. The first character of the fourth group should be 8, 9, a or b for the RFC 4122 variant.
One hundred per click. Larger values are capped to 100, and you can click generate again for more.
They are random, but a UUID is meant to identify something, not to protect it. For passwords or access tokens use the password or random string generators and follow your platform's security guidance.
The tool outputs lowercase hyphenated values. Use a text editor or find and replace to change the case or remove hyphens after copying.
Reference: MDN Web Docs