UUID Generator
Generate RFC 4122 version 4 UUIDs in bulk from a cryptographically secure source.
About this tool
A UUID is a 128-bit identifier you can hand out without asking a central server for permission, so two machines can generate IDs independently and still never collide. Most developers reach for a UUID generator when seeding a database with test rows, naming uploaded files, tagging log events, or filling in a primary key by hand during a migration. Pasting a thousand fresh IDs into a fixture file is a different job from copying one, which is why bulk generation is the default here.
This generator calls the browser's built-in crypto.randomUUID(), which draws
from the operating system's cryptographically secure random number generator rather than
Math.random(). Nothing leaves the page: no network request, no server round
trip. That matters more than usual for IDs, since an online generator that returns results
from a server has already seen every value you were about to treat as yours.
Frequently asked questions
Are these UUIDs random enough to be unique?
They come from crypto.randomUUID(), which is seeded by the operating system's cryptographically secure random number generator, not Math.random(). A version 4 UUID carries 122 random bits. Even at a billion per second, you would need decades of continuous generation before a single collision becomes likely.
Are the generated UUIDs sent to a server?
No. Generation happens entirely in your browser, with no network request at any point. That is worth checking on any online generator: if the values are produced server-side, whoever runs that server has seen every ID you just claimed as unique to your system.
What is the difference between UUID v4, v1 and v7?
v4 is fully random and the safe default for most applications. v1 encodes a timestamp and a MAC address, which leaks when and where the ID was created. v7 also starts with a timestamp, so IDs sort by creation time and behave better as database primary keys. This tool produces v4.
Why would I remove the hyphens or add braces?
Formatting conventions differ by system. The canonical form is 8-4-4-4-12 with hyphens. Some databases and APIs store the 32 hex characters without them to save space. The braced form comes from Microsoft's GUID convention and shows up in the Windows registry, COM interfaces, and .NET code.