UUID Generator
Generate one or many version 4 UUIDs in a single click. Values come from the browser's cryptographic random number generator, so they are safe to use as real identifiers.
UUIDs
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About this tool
A UUID version 4 is a 128-bit identifier where 122 bits are random. The chance of generating the same value twice is small enough that databases, message queues and distributed systems treat them as globally unique without any coordination.
The canonical form is 36 characters — 32 hexadecimal digits in five groups separated by hyphens. Microsoft ecosystems often call the same thing a GUID and sometimes wrap it in curly braces.
Frequently asked questions
- What is the difference between a UUID and a GUID?
- They are the same 128-bit identifier. GUID is Microsoft's name for it; UUID is the term used in the RFC 4122 standard.
- Are these UUIDs really random?
- Yes. They come from `crypto.randomUUID()`, which uses the operating system's cryptographically secure random source — not `Math.random()`.
- Can two UUIDs collide?
- In theory yes, in practice no. You would need to generate about 2.7×10¹⁸ UUIDs before reaching a one-in-a-billion chance of a single collision.
- Should I use a UUID as a database primary key?
- It works well for distributed systems, but random UUIDs fragment B-tree indexes. If write performance matters, consider UUID v7 or a sequential identifier.
- What version does this tool generate?
- Version 4, the fully random variant. You can recognise it by the `4` at the start of the third group.