Developer tools
UUID Generator
Generate random version 4 or time-ordered version 7 UUIDs, one at a time or in bulk, ready to copy.
Click an ID to copy it.
What it is for
A UUID (universally unique identifier, also called a GUID) is a 128-bit value written as 32 hexadecimal digits in five groups, such as 3f2c9a1e-7b4d-4e8a-9c21-5d6f7a8b9c0d. Because the space of possible values is so large, two systems can generate IDs independently with no realistic chance of a collision, which makes UUIDs a common choice for database keys, API resources, file names and request tracing. This generator produces version 4 UUIDs from your browser's cryptographic random number generator, and version 7 UUIDs that start with a timestamp so they sort in creation order.
How to use it
- Choose version 4 for fully random IDs or version 7 for time-ordered IDs, then set how many you need.
- Click Generate for a fresh batch. Uppercase and No hyphens change the formatting without changing the values.
- Copy one ID by clicking it, or use Copy all to grab the whole list, one per line.
Questions
- Which version should I use?
- Version 4 is the safe default and works everywhere. Version 7 is better as a database primary key because new values sort after old ones, which keeps indexes compact. Both are equally unique.
- Are these UUIDs really unique?
- Effectively yes. A version 4 UUID has 122 random bits, so you would need to generate about 2.7 quintillion of them before a duplicate becomes likely. They are random, not registered, so nobody checks them against a list.
- What do the 4 and 7 in the third group mean?
- The first digit of the third group is the version number. The first digit of the fourth group is the variant, which is 8, 9, a or b for standard UUIDs. These bits are fixed, so they are not part of the randomness.
- Are the IDs generated on a server?
- No. They come from the Web Crypto API in your browser, which uses the operating system's secure random source. Nothing is sent or stored.