UUID Generator
Generate random version-4 UUIDs in your browser.
Generate one or many random version-4 UUIDs (universally unique identifiers) instantly — perfect for database keys, test data and APIs. Hit Regenerate for a fresh set.
Formula / method
Examples
e.g. 3f2a7c1e-…-…
five UUIDs, one per line
Identifiers that never collide
A UUID is a 128-bit identifier written as 32 hex digits in five groups. Its purpose is to let independent systems each create IDs that are, for all practical purposes, guaranteed not to clash — without any central authority handing them out.
Why they are practically unique
A version-4 UUID fills most of its bits with random data, giving so many possibilities that the chance of two matching is negligible. That makes UUIDs ideal for database keys, request IDs and file names in distributed or offline-first apps. This generator creates them in your browser; the What Is a UUID guide covers the versions.
Where it's used
- Assigning a unique primary key to a database row without a central counter
- Naming uploaded files or storage objects so two never collide
- Generating request or trace IDs for logging across microservices
- Creating idempotency keys so a retried API call isn't processed twice
- Tagging records created offline on a client before they sync to a server
Real-world examples
- A backend mints a v4 UUID like f47ac10b-58cc-4372-a567-0e02b2c3d479 as the id for a new order.
- A file-upload service names each stored blob with a fresh UUID so uploads never overwrite each other.
- Two offline mobile clients each create records with UUIDs and sync later with no key clashes.
A bit of history
The UUID format was standardised in RFC 4122 in 2005 (and refreshed by RFC 9562 in 2024). Earlier universally unique identifiers trace back to the Apollo Computer Network Computing System in the 1980s.
Did you know?
A version-4 UUID carries 122 random bits — so many possible values that the odds of two randomly generated ones ever colliding are vanishingly small, which is exactly why separate systems can mint them with no coordination.
FAQ
What is a UUID?
A 128-bit identifier so large that random ones are effectively never repeated — ideal for unique keys without a central counter. Version 4 is fully random.