Create unique IDs for databases, files, test data or orders — one at a time or 500 at once. Also checks if a UUID is valid.
Check a UUID
What this tool does
A UUID (also called GUID) is a 128-bit ID that looks like 3f2b8c1e-7a4d-4e0b-9c21-5d8f6a1b2c3d. The chance that two random UUIDs are the same is so small that you can create them anywhere, without asking a central server. v4 is fully random. v7 starts with the current time, so new IDs sort after old ones — databases like that because it keeps their index fast.
How to use it
Pick v4 (most common) or v7 (for database keys).
Choose how many and the format you need.
Tap Generate, then Copy all or download.
To check an existing ID, paste it into Check a UUID.
How to read the result
The 13th character shows the version (4 or 7). The checker tells you the version, and for v7 it also shows the date and time the ID was made. Hyphens, braces and upper/lower case do not change the value — they are only formats different systems prefer.
When it is useful
Primary keys in MySQL, PostgreSQL or SQLite.
Unique file names for uploads so two files never overwrite each other.
Test data for apps and forms.
Order IDs, invoice references or tracking codes that cannot be guessed easily (v4).
What it cannot do
A UUID is an ID, not a password or secret token — do not use it to protect private pages.
v7 shows when it was made; use v4 if the creation time should stay private.
It cannot check whether an ID already exists in your database.
Older versions (v1, v3, v5) are not generated here, but the checker recognises them.
Privacy: everything runs inside your browser. Your text is not sent to our server and is not saved.
Questions people ask
Can two UUIDs ever be the same?
In theory yes, in practice no. With v4 you would need to make billions of IDs every second for many years to have a real chance of one duplicate.
Should I use v4 or v7?
Use v7 for database primary keys because it sorts by time. Use v4 when you want no hidden information at all in the ID.
What is the difference between UUID and GUID?
None in practice. GUID is Microsoft's name for the same thing. Windows tools often write it in UPPERCASE with braces.
Is crypto.randomUUID secure?
Yes. It uses the browser's cryptographic random generator. This page uses it when your browser supports it.
How do I store a UUID in MySQL?
Use CHAR(36) for simplicity, or BINARY(16) to save space. With v7 IDs, inserts stay fast because new rows go to the end of the index.