UUID Generator

A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 32 hexadecimal digits in five hyphen-separated groups — for example 123e4567-e89b-12d3-a456-426614174000. Because the space of possible values is enormous, two independently generated UUIDs are, for all practical purposes, never the same. That makes them ideal for database primary keys, file names, request IDs and any case where you need a unique label without a central authority handing them out.

Yes. Version 4 UUIDs are built from the browser’s cryptographically secure random source (crypto.getRandomValues / crypto.randomUUID), the same generator used for security-sensitive tokens — not Math.random(). A v4 UUID carries 122 random bits, so the chance of a collision is negligible even across billions of values. They are perfectly safe for production identifiers. They are not secrets in themselves, though, so do not use a UUID in place of a password or an access token.

Version 1 is time-based: it encodes a timestamp and a node identifier, so values are roughly ordered by creation time (this tool uses a random node, as a browser cannot read your network card). Version 4 is fully random with no embedded information — the most common choice when you just need uniqueness. Version 7 (from the newer RFC 9562) is the modern time-ordered option: it puts a millisecond Unix timestamp at the front followed by random bits, so the IDs sort chronologically while staying unguessable. Use v4 by default, or v7 when you want database-friendly, sortable keys.

Random v4 UUIDs scatter inserts all over a B-tree index, which can hurt write performance and index locality on large tables. Version 7 starts with a timestamp, so newly created rows cluster together at the “end” of the index — much like an auto-incrementing key, but still globally unique and generated client-side. If you are picking a UUID as a primary key for a busy table, v7 is usually the better default.

No. Every UUID is generated in your browser using the built-in Web Crypto API. Nothing is sent anywhere — there is no request carrying your values, and you can confirm that by watching your browser’s network panel while you click Generate. The bulk list, the copy action and the share link all stay on your device. The share link carries the values in the URL fragment, which browsers never transmit to a server.

Yes. Set the count to generate up to a thousand at once, one per line, then copy the whole list or download it as a text file. The format toggles let you switch to uppercase, strip the hyphens, or wrap each value in braces for Microsoft-style GUIDs ({xxxxxxxx-…}). Whatever you pick is applied to the entire batch, so you get a consistent list ready to paste into code, a seed file or a spreadsheet.