This generates version 4 UUIDs, identifiers built from random data and formatted as the standard 36 character string used throughout software to label records, sessions, and objects in a way that's essentially guaranteed never to collide with another one. It's faster than calling a library function in your own code when all you need is a handful of values for a test or a quick script.
How to use it
- Enter how many you want.
- Click generate.
- Look over the list in the output box.
- Copy the whole list, or just the ones you need.
- Generate again anytime for a fresh, independent set.
When it helps
- Assigning a unique ID to a new database record without a centralized counter.
- Generating session or request IDs for tracking a distributed system.
- Creating placeholder test data with realistic looking IDs.
- Naming temporary files in a way that avoids collisions across systems.
- Tagging objects in a system where multiple services generate IDs independently.
Good to know
- Version 4 UUIDs come from random data, which is why the same value essentially never repeats across separate runs.
- They aren't sequential, so you can't use them to infer creation order the way an auto incrementing ID would let you.
- Generate a batch at once rather than one at a time if you need several, since bulk generation saves clicking.
- When seeding a test database, generate all the UUIDs you'll need up front in one batch rather than generating them one at a time during separate test runs.
- If you need IDs for a small internal tool rather than a distributed system, a simpler counter might actually suit you better than a UUID, which is built for a larger scale problem.
Where UUIDs help
Because UUIDs can be generated anywhere without coordination, they suit ids in distributed systems and offline apps. Their size and randomness make accidental clashes extremely unlikely.
Questions
What does version 4 actually mean?
It refers to how the UUID is generated. Version 4 comes almost entirely from random numbers, unlike other versions that build in a timestamp or a hardware identifier.
How likely is a collision between two generated UUIDs?
Astronomically unlikely. A version 4 UUID has 122 random bits, so you'd need to generate an enormous number before a collision became a realistic concern.
Can I use these as database primary keys?
Yes, they're commonly used that way, especially in distributed systems where several services need to generate unique IDs without coordinating with a central database.
Are UUIDs the same as GUIDs?
Yes, GUID is essentially Microsoft's name for the same concept, and the two terms are generally used interchangeably.
Can I remove the dashes from a generated UUID?
Yes, some systems expect a UUID without them, as a 32 character string. You can remove them yourself, though the standard format keeps them by default.
Are UUIDs case sensitive?
The letters in a UUID are conventionally lowercase, but most systems that accept UUIDs will treat uppercase and lowercase versions as equivalent.