UUID Generator

About this tool

A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier), is a 128-bit identifier formatted as 32 hexadecimal digits in the pattern 8-4-4-4-12 (e.g. 550e8400-e29b-41d4-a716-446655440000). UUIDs are used as primary keys in databases, session tokens, file names, and anywhere a globally unique value is needed without coordination between systems. This tool generates Version 4 UUIDs, where 122 bits are random, making the probability of a collision astronomically small. All UUIDs are generated locally in your browser using the Web Crypto API.

How to use

1. 1Click "Generate" to create a single UUID v4.
2. 2Set a count in the bulk field and click "Generate Bulk" to create multiple UUIDs at once.
3. 3Click the copy icon next to any UUID to copy it to your clipboard.
4. 4All UUIDs are generated locally using the Web Crypto API — nothing is sent to a server.

Frequently asked questions

What is UUID v4?

UUID version 4 is generated from random numbers. It has the form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where 4 marks the version and y is one of 8, 9, a, or b. The remaining 122 bits are random, giving about 5.3 × 10^36 possible values.

Can two generated UUIDs be the same?

In theory yes, but in practice no. With 122 random bits, you would need to generate approximately 2.7 × 10^18 UUIDs before a 50% chance of a single collision (the birthday problem). In real-world use, this is considered impossible.

UUID vs GUID — what is the difference?

They refer to the same concept. UUID is the open standard (RFC 4122). GUID (Globally Unique Identifier) is Microsoft's name for the same thing, used in Windows and .NET. They are interchangeable.

What is UUID v1 vs v4?

UUID v1 is generated from the current time plus the machine's MAC address, making it traceable to a specific machine and moment. UUID v4 is purely random and reveals nothing about where or when it was generated, which is why v4 is preferred for most modern use cases.