UUID and GUID generator: v4, v7 and v1 online
UUID v4, v7 and v1 in batches of up to 1,000, with formats and encodings.
What is generated
v4 is the most common variant: 122 random bits and no information about time or hardware. v7 is the modern RFC 9562 standard: the first 48 bits hold a millisecond timestamp, the rest is randomness, so values sort by creation date. v1 is a historical format with time and node; it is useful for compatibility, but time and node are visible from the outside.
A batch of v7 is generated with a monotonic counter: if several values fall into the same millisecond, the random part is incremented and the strings still grow. For v4 and v1 a duplicate check is enabled.
Formats and encodings
Hyphens are on by default — that is how a UUID looks in documentation and logs. Braces are for C# and .NET — the value in curly brackets; quotes and commas are for inserting a list straight into SQL or JSON. Base64 shrinks the string from 36 characters to 24 and suits compact storage in binary fields; URL-encode is useful when the identifier ends up in a query parameter.
Why not Math.random
Values are collected from crypto.getRandomValues — the cryptographic source of the browser. Plain Math.random() gives a predictable sequence: knowing a few values, you can restore it. For test data that does not matter; for session identifiers it does.
Generation happens locally: no value is sent to a server. Copy the list or download it as a file — history is not saved in the browser.
Frequently asked questions
What is the difference between a UUID and a GUID?
Essentially none: GUID is Microsoft’s historical term, UUID comes from RFC 9562. It is the same 128-bit identifier; only the names in documentation and APIs differ.
Which version should I choose?
v4 for random identifiers. v7 for database primary keys where time ordering matters. v1 embeds the time and a node, so it is a poor fit for public links.
Where does the randomness come from?
From crypto.getRandomValues, the browser’s cryptographic source. Math.random() is not suitable for identifiers: its sequence is predictable.
Can I generate 1,000 at once?
Yes, and the values do not repeat: a batch of v7 uses a monotonic counter, while v4 and v1 are checked for duplicates.
Related tools
Checked: 26 October 2026. For reference only — the result depends on the material and the skill of the installer.