UUID generator
Generate random or time-ordered UUIDs in bulk, formatted the way you need.
How it works
Inside a UUID
Every UUID is 128 bits. A few of them say which version it is (the first digit of the third group, 4 or 7 here) and which variant (8, 9, a or b at the start of the fourth group). The rest carry the actual value.
- Version 4: 122 random bits. No meaning, no order.
- Version 7: the first 48 bits are the creation time in milliseconds, then 74 random bits. Newer IDs sort after older ones, which databases like.
Both are defined in RFC 9562 (2024), which updated the original UUID standard. DevBenchr uses your browser's cryptographically secure random number generator for the random bits.
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Frequently asked questions
What is a UUID?
A UUID (universally unique identifier), also called a GUID, is a 128-bit number written as 32 hexadecimal digits in five groups, like 550e8400-e29b-41d4-a716-446655440000. It lets any system create IDs without asking a central server, with practically no risk of two being the same.
Should I use version 4 or version 7?
Version 4 is fully random and the most widely supported. Version 7 starts with a timestamp, so new IDs sort after older ones. That makes v7 a better choice for database primary keys, because inserts stay in order and indexes stay efficient.
Can two UUIDs ever be the same?
In theory yes, in practice no. A version 4 UUID has 122 random bits: you would need to generate about a billion UUIDs per second for around 85 years to have a 50% chance of a single duplicate.
Are these UUIDs secure?
They are generated with the browser's cryptographically secure random number generator. Still, don't use a UUID as a password or secret token: it isn't designed for that, and a version 7 UUID reveals when it was created.