UUID v4 Generator
Generate up to 100 random version 4 UUIDs for identifiers, mock data or testing. Values are created on your device and are not saved by the site.
Runs locally in your browser
Generated with your browser’s cryptographic random generator.
Discuss a result
Write a short summary and review it before posting. Your tool inputs are never copied automatically.
What is the UUID v4 Generator?
Generate up to 100 random version 4 UUIDs for identifiers, mock data or testing. Values are created on your device and are not saved by the site.
How to use it
- 1Choose a quantity from one to one hundred.
- 2Select Generate UUIDs.
- 3Copy the resulting identifiers.
How it works
The browser’s crypto.randomUUID API creates each UUID v4 with a cryptographically secure random source.
Fixture IDs
Generate five UUIDs to assign unique identifiers to five test records without contacting an API.
Limitations & notes
- UUIDs identify records; they are not passwords or secret tokens.
- The API requires a secure browser context.
Frequently asked questions
Can two UUID v4 values ever collide?
In theory yes, in practice no. A version 4 UUID has 122 random bits, about 5.3 times 10 to the 36th possible values. You would need to generate roughly 103 trillion UUIDs to reach a one in a billion chance of a single duplicate. Real collisions almost always come from a broken random generator or copied values, not chance, which is why this tool uses the browser's cryptographic generator.
How can I tell that a UUID is version 4?
Look at the third group. A UUID is written as 8-4-4-4-12 hexadecimal characters, and in version 4 the third group always starts with 4, as in 3f2b9c1e-7a4d-4e21-9b0c-5d6e7f8a9b0c. The first character of the fourth group is 8, 9, a or b, which marks the standard RFC variant. Values from this tool are lowercase, which is the canonical form; most systems accept either case.
Should I use UUID v4 or v7 for database primary keys?
UUID v7, defined in RFC 9562 in 2024, starts with a millisecond timestamp, so new keys arrive in roughly increasing order. That keeps B-tree indexes compact and inserts fast in databases like PostgreSQL and MySQL. Version 4 is fully random, which scatters inserts across the index but reveals nothing about when a record was created. This tool generates v4 only, which suits test data, public identifiers and systems that do not depend on insert order.
Is a UUID the same as a GUID?
Yes, for practical purposes. GUID is Microsoft's name for the same 128-bit format, used in Windows, .NET and SQL Server's uniqueidentifier type. A GUID is often shown in uppercase or wrapped in braces, like {3F2B9C1E-...}, but the value is identical. You can paste the lowercase output from this tool into .NET, SQL Server or Azure tools, and add braces or change case only if a specific config file expects them.
How many UUIDs can I generate at once here?
From 1 to 100 per click. Enter the quantity, press Generate UUIDs and copy the list, which has one value per line, ready for a spreadsheet column or a SQL insert script. Click again for a fresh batch; nothing is stored between clicks or sent to a server. For thousands of values, use a script, for example crypto.randomUUID() in a loop in Node.js or uuid.uuid4() in Python.
No directly related discussion yet.
Start a focused thread and share the question this tool helped you explore.
Ask the community about UUID v4 Generator