About the UUID Generator
A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value used to label records, files and messages without a central authority handing out numbers. This generator creates UUIDs that follow RFC 9562, the current standard. Version 4 is fully random; version 7 starts with a timestamp, so newer IDs sort after older ones — which makes it a better choice for database primary keys.
How to use the UUID Generator
- Choose UUID v4 or v7.
- Enter how many you need (up to 1,000).
- Optionally switch to uppercase or remove the hyphens.
- Press "Copy all" to copy them, one per line.
The formula behind it
v4 or v7 — which should I use?
Use v4 when you only need an unpredictable unique ID, such as a session or file name. Use v7 for database keys: because v7 values increase over time, new rows are added at the end of an index instead of at random positions, which keeps inserts fast in PostgreSQL, MySQL and similar databases.
Can two UUIDs ever be the same?
In theory yes, in practice no. A v4 UUID has 122 random bits. You would need to generate around 2.7 quintillion of them to have even a 50% chance of a single duplicate.
Frequently asked questions
Is a GUID the same as a UUID?
Yes. GUID is Microsoft’s name for the same 128-bit identifier format.
Should I use UUIDs as passwords or secret tokens?
No. v7 UUIDs reveal their creation time, and UUIDs are not designed as secrets. Use the password generator or a dedicated token generator instead.
Are the UUIDs generated on your server?
No. They are generated in your browser using the Web Crypto API.
Sources
About the author: Ahmed Bilal
Ahmed Bilal is the founder of VolexTool and builds and maintains every calculator on the site. Tax rates and thresholds are taken directly from official sources such as GOV.UK, HMRC, the Canada Revenue Agency and the Australian Taxation Office, the formula is shown on every page, and each update must pass more than 600 automated checks before it goes live. Ahmed is not a tax adviser: for decisions about your own situation, speak to a qualified accountant or financial adviser.