A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 32 hexadecimal digits in five groups, like 550e8400-e29b-41d4-a716-446655440000. Its purpose is to give you an identifier that is unique without a central authority — so two systems can generate IDs independently and practically never collide. To generate a UUID, click Generate in a UUID tool. Here is how they work and when to use them.
Choose a count from 1 up to 1000 to generate UUIDs in bulk.
Optionally output uppercase or strip the dashes to match your code style.
The tool uses the browser’s cryptographic random source to create version 4 UUIDs.
Copy a single UUID or all of them at once, ready to paste into your database or code.
What is a version 4 UUID?
A version 4 UUID is generated from random numbers. With 122 random bits, the chance of two colliding is astronomically small, which is why v4 is the default choice for database keys and request IDs. The UUID generator uses the Web Crypto API, so the randomness is cryptographically strong.
When should you use a UUID?
Use a UUID when you need a unique id that can be created anywhere — primary keys in distributed databases, request/trace ids in logs, idempotency keys, file names, and message ids. They avoid the coordination an auto-increment integer needs, at the cost of being longer.
UUID vs auto-increment id
Auto-increment ids are short and ordered but require a single source of truth and leak record counts. UUIDs are globally unique and safe to expose, but larger and unordered (which can affect index locality). Many teams use UUIDs for public ids and integers internally. For other ids, see the rest of the developer tools.
Tip: If you need time-sortable ids, look at UUID v7 — but for general uniqueness, v4 is the simplest and most widely supported choice.
Generate UUIDs now
Create cryptographically-random v4 UUIDs in bulk — free, in your browser.
Open the UUID Generator →Frequently Asked Questions
What is a UUID?
A 128-bit universally unique identifier written as 32 hex digits in five dash-separated groups. It is unique without any central coordination.
Are UUIDs truly unique?
Not guaranteed, but the collision probability for random v4 UUIDs is so small it is treated as unique in practice.
How do I generate a UUID?
Click Generate in a UUID tool. This one creates cryptographically-random v4 UUIDs in your browser, in bulk if needed.
Is a GUID the same as a UUID?
Yes — GUID is Microsoft’s name for the same 128-bit identifier.