UUID Generator
Generate random v4 or time-ordered v7 UUIDs, one or a hundred at a time. Produced in your browser from its cryptographic random source, never sent anywhere.
UUIDs
About this tool
A UUID is 128 bits written as 32 hex digits, unique enough that separate systems can mint identifiers without coordinating. Version 4 fills almost all of it with randomness, which is what makes it collision-proof in practice and unguessable. Version 7 spends the first 48 bits on a millisecond timestamp instead, trading a little entropy for values that sort by creation — noticeably kinder to a database index. Both are generated here by crypto.getRandomValues, the same source used for keys and tokens.
How to use it
- 1Pick the version — v4 for opaque identifiers, v7 for database keys.
- 2Choose how many you need, and adjust case or hyphens if the target system is picky.
- 3Press Copy for the whole list, or Regenerate for a fresh batch.
Frequently asked questions
›Are these UUIDs safe to use as identifiers?
Yes. They come from the browser's cryptographic random source, not Math.random, so collisions are not a practical concern: a v4 UUID has 122 random bits, and you would need to generate billions per second for decades before one repeated.
›What is v7 and when should I use it?
A v7 UUID starts with a 48-bit millisecond timestamp, so the values sort by creation time. That matters in a database: random v4 keys scatter writes across a B-tree index, while v7 keys append in order and keep the index compact. Use v7 for primary keys, v4 when the identifier should reveal nothing.
›Can I get them without hyphens, or uppercase?
Both toggles are in the toolbar. The hyphens are only formatting — the same 128 bits either way — but some systems store the compact 32-character form, and older Microsoft tooling expects uppercase.
›Are they generated on a server?
No, and that is the point. Every value is produced in your browser and never transmitted, so nothing you copy from here has been seen by anyone else.
›What is the nil UUID?
All zeros — 00000000-0000-0000-0000-000000000000. It is the conventional way to say "no identifier" in a field that must contain a UUID.