UUID Generator
A fresh v4 UUID is ready below — click it to copy, or generate a batch.
Click the UUID to copy it
Options
Processed on your device — nothing is sent anywhere.
How it works
- A random v4 UUID appears as soon as the page loads. Click it to copy, or click New UUID for another one.
- Need more than one? Enter a count between 1 and 100 and click Generate to build a list.
- Click Copy all to put the whole list on your clipboard, one UUID per line. Open Options for uppercase or hyphen-free output.
Frequently asked questions
- What is a v4 UUID?
- A version 4 UUID is a 128-bit identifier generated entirely from random data, written as 32 hexadecimal digits in five hyphen-separated groups. Unlike version 1, it contains no timestamp or hardware address, so it reveals nothing about when or where it was created. It is the most widely used UUID version for database keys, request IDs and general-purpose identifiers.
- Can two generated UUIDs ever collide?
- In practice, no. A v4 UUID has 122 random bits, which means you would need to generate roughly a billion UUIDs every second for decades before a duplicate becomes even remotely likely. This tool uses crypto.randomUUID, which draws from your browser’s cryptographically secure random number generator rather than a weaker pseudo-random source.
- Are the UUIDs generated on a server?
- No. Every UUID is created locally in your browser using the built-in Web Crypto API — nothing is requested from or sent to any server. The identifiers never leave your device unless you paste them somewhere yourself, so they are safe to use for keys and tokens in private projects.
- What is the difference between UUID v4 and v7?
- Version 7 UUIDs start with a millisecond timestamp, so they sort chronologically — a real advantage for database primary keys because inserts stay ordered and indexes fragment less. Version 4 is pure randomness, which makes it slightly more private and universally supported. If your database or library does not offer v7 yet, v4 remains the safe default.
- Are UUIDs case-sensitive, and does the hyphen format matter?
- The RFC specifies lowercase output but requires parsers to accept both cases, so aBc and ABC forms identify the same value. Some systems, notably Microsoft products, display them uppercase. Hyphens are formatting only — removing them saves four characters for compact storage, and this tool can output either style with the same underlying value.
About this tool
This UUID generator gives you a fresh version 4 UUID the moment the page loads — click it once and it is on your clipboard. When one is not enough, enter any count up to 100 and generate a whole list, then copy it in one click with each identifier on its own line. Options let you switch to uppercase output or strip the hyphens for systems that store the compact 32-character form.
Generation happens entirely in your browser through crypto.randomUUID, part of the Web Crypto API. That function draws from the operating system’s cryptographically secure random source, the same quality of randomness used for encryption keys — not a predictable Math.random substitute. Because no server is involved, the identifiers cannot be logged or observed anywhere: they exist only on your device until you paste them into your own project.
UUIDs solve the problem of creating identifiers without coordination. Two developers, two services or two offline devices can each mint IDs simultaneously with essentially no risk of collision, which is why v4 UUIDs appear as database primary keys, API request IDs, file names for uploads, order and session tokens, and correlation IDs in distributed tracing. A batch from this page is handy for seeding test fixtures, filling spreadsheet columns, or preparing configuration files before the code that would normally generate them exists.
A few practical notes. Store UUIDs in a native uuid or binary column when your database offers one — as plain text they take 36 bytes instead of 16 and compare more slowly. If insert-order matters at scale, consider time-ordered v7 identifiers to keep indexes tight; v4 values scatter randomly across an index. And treat a UUID as an identifier, not a secret: 122 random bits are hard to guess, but real access control belongs in authentication, not in an unguessable URL.