Generate universally unique identifiers in bulk with your browser’s secure random number generator. Choose random v4 or time-ordered v7, format them as you like, and paste any UUID below to see its version and variant.
A UUID (universally unique identifier) is a 128-bit value written as 32 hexadecimal digits in five groups, such as 123e4567-e89b-12d3-a456-426614174000. Systems can create them independently, without talking to a central server, and still expect no two to collide. That makes them popular as database keys, file names, request IDs and message identifiers.
| Version | How it is made | Good for |
|---|---|---|
| v4 | 122 random bits | General purpose IDs where order does not matter |
| v7 | 48-bit Unix millisecond time followed by random bits | Database primary keys, because new values sort after older ones and keep indexes compact |
Random v4 values are the usual default. Time-ordered v7 values are defined in RFC 9562 and reduce index fragmentation in databases that store keys in sorted order, at the cost of revealing roughly when each ID was created.
The values come from crypto.randomUUID() or the browser’s cryptographic random source, and they are created on your device without being sent anywhere. A UUID is an identifier, not a secret: do not use one as a password or access token unless you know it was generated randomly and is long enough for your threat model.
Can two UUIDs ever be the same? It is theoretically possible but practically negligible. With 122 random bits, you would need to generate billions of v4 UUIDs per second for many years before a collision becomes likely.
What is the difference between UUID and GUID? They are the same thing. GUID is the term Microsoft uses; the format and versions are identical.
Why use UUID v7 instead of v4 for database keys? Because v7 begins with a timestamp, new rows are inserted near the end of the index instead of at random positions, which usually improves write performance and cache use.
Are the UUIDs generated here sent to a server? No. They are created locally in your browser and never leave your device.
Can I remove the hyphens? Yes. Tick No hyphens to get a plain 32-character string, which some systems and databases prefer.