UUID Generator

This tool generates version 4 UUIDs — 128-bit identifiers made almost entirely of random bits — for use as database keys, request IDs, file names or test data. It can also tell you whether a string is a valid UUID and which version it is.

1. Choose how many UUIDs you need, up to 500.
2. Pick a format: lower or upper case, with or without hyphens, with or without braces.
3. Press "Generate UUIDs". Copy one by clicking its copy button, or copy them all at once.
4. To check an existing ID, paste it into "Check a UUID".

• Only version 4 (random) UUIDs are generated. Time-ordered versions such as v7 are not.
• A UUID is unique by probability, not by guarantee — though a collision among random v4 UUIDs is so unlikely it can be ignored in practice.
• UUIDs identify things; they are not passwords or secret tokens.
• UUIDs are generated by your browser’s built-in cryptographic random number generator. None are sent anywhere or remembered, so each one is new and known only to you.

They are the same format. GUID is the name Microsoft uses; UUID is the name used in the standard. Windows tools often show GUIDs in upper case with braces, which the format options here reproduce.

In theory yes, in practice no. With 122 random bits you would need to generate billions of UUIDs every second for decades before a duplicate became likely.

Yes. They come from crypto.getRandomValues, the same cryptographically secure source browsers use for security features, not from Math.random.