UUID v4 Generator
Generate secure random UUIDs (version 4) in your browser using the cryptographic random source. Choose a count, toggle uppercase or dash-free format, and copy the whole list with one click.
How to use
- Choose how many UUIDs you need — from 1 to 100; five are generated by default.
- Toggle uppercase letters or dash-free format if your target system needs it.
- Click Generate, then copy the entire list with one click and paste it wherever you need it.
Frequently asked questions
What is a UUID v4?
A UUID is a 128-bit identifier written as 32 hexadecimal digits in eight groups. Version 4 derives almost all of those bits from random data: 122 random bits remain after reserving 6 for the version and variant markers. That makes v4 the standard choice when you need unique IDs without a central authority to coordinate them.
How unlikely is a collision?
With 122 random bits the probability that a single pair of UUIDs matches is astronomically small — roughly one in 5.3 × 10^36. Even if you generated one billion UUIDs every second for a hundred years, the chance of seeing one collision would remain far below one in a billion. Duplicate IDs are, in practice, not a concern.
Are these UUIDs cryptographically secure?
Yes. The tool fills 16 bytes from crypto.getRandomValues, the browser cryptographic random generator, and sets the version and variant bits exactly as the RFC 4122 layout requires. The values are suitable for session tokens, database keys, file names and any other place where unpredictable identifiers matter.
Is anything logged or stored?
No. Generation happens entirely in your browser: no network request is made, nothing is uploaded, and nothing is saved. Once you leave the page the UUIDs are gone unless you copied them, so treat the list like any other locally produced data.
When should I strip dashes or use uppercase?
Formatting is cosmetic — every variant encodes the same 128 bits. Remove dashes when a database column, URL or legacy system rejects the standard layout, and use uppercase when a style guide asks for it. This tool applies either option to the whole list before you copy it.