UUID Generator
Click below to generate a random, version-4 UUID you can use immediately.
What is UUID Generator?
A UUID (Universally Unique Identifier) is a 128-bit value used to identify information without a central authority handing out IDs. This tool generates version 4 UUIDs, the most common variant, where 122 of those bits are chosen at random — the remaining 6 bits are fixed to mark the version and variant, which is why every UUID v4 looks like xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, with a 4 in the same position and y always one of 8, 9, a, or b.
Generation uses the Web Crypto API's cryptographically secure random number generator (crypto.randomUUID()), not a plain pseudo-random function, so the output is suitable for security-sensitive identifiers, not just display IDs.
| UUID v1 | UUID v4 (this tool) | |
|---|---|---|
| Based on | Timestamp + MAC address | Pure randomness (122 random bits) |
| Can leak info | Yes — creation time and machine identity | No |
| Sortable by creation time | Yes, roughly | No |
| Typical use | Legacy systems, distributed logging | Database keys, API IDs, general use |
- Example output: 3fa85f64-5717-4562-b3fc-2c963f66afa6 — note the fixed 4 and the b in the third and fourth groups.
Reference: RFC 4122 — UUID specification
How to use UUID Generator
- Click "Generate UUID".
- Copy the value using the copy button.
- Generate again for a new one — there's no limit and nothing is stored.
Common errors
- "I got the same UUID twice" — with 122 random bits, a collision is astronomically unlikely (you'd need roughly a billion UUIDs a second for about 85 years before a 50% chance of one collision); if it ever happens, check that your browser's random number generator itself is intact.
- "I need a UUID without dashes" — strip them yourself if your target system requires the 32-character unformatted form; the canonical, dashed form is what's generated here since it's what RFC 4122 specifies.
FAQ
Is this UUID generator free to use?
Yes, generation is unlimited and free, and runs entirely in your browser.
Does the UUID get sent to a server or stored anywhere?
No. Generation happens client-side using your browser's built-in crypto.randomUUID() function — nothing is transmitted or logged.
What's the difference between UUID v4 and other UUID versions?
UUID v1 encodes the current timestamp and the generating machine's network identifier, which can leak information about when and where it was created. UUID v4 is purely random, which is why it's the standard choice for most applications today. This tool generates v4 only.
Can I use a UUID as a database primary key?
Yes, it's a common pattern — UUIDs avoid the coordination problem of auto-incrementing IDs across distributed systems, at the cost of being larger (16 bytes) and less index-friendly than a plain integer.