# UUID Generator - Version 4, Free, Local

Page: https://hirantha.me/tools/uuid-generator
Part of: Hirantha Sandaruwan Lakshan free tools (https://hirantha.me/tools)
Updated: 2026-07-31

Generate random version 4 UUIDs, one at a time or in bulk.

This is a free tool that runs in the browser: open the page to use it. File tools process files on the visitor's own device; files are never uploaded or stored. No account, sign-up, payment or watermark.

Generate random version 4 UUIDs (universally unique identifiers), one at a time or dozens at once, using your browser's cryptographic random number generator.

A version 4 UUID is 122 bits of randomness formatted into the standard 8-4-4-4-12 hyphenated layout, with a few fixed bits marking it as version 4 and its variant.

The randomness comes from crypto.randomUUID(), a browser-native method built on the same cryptographically secure random source used elsewhere in the Web Crypto API, not a predictable pseudo-random function.

With 122 random bits, the chance of two independently generated version 4 UUIDs colliding is negligible even across billions of IDs, which is why they're commonly used as database primary keys and unique identifiers.

Q: Is my generated UUID sent anywhere?
A: No, UUIDs are generated entirely in your browser tab.

Q: How likely is a collision between two UUIDs?
A: Vanishingly unlikely - version 4 UUIDs have 122 random bits, so generating billions of them still carries negligible collision risk.

Q: Can I generate more than one at a time?
A: Yes, set the quantity to generate a batch and copy them all together.

Q: What's the difference between UUID and GUID?
A: They're effectively the same concept - GUID is Microsoft's term for the same kind of identifier defined by the UUID standard.

Q: Are UUIDs random or sequential?
A: The version generated here is random. That makes collisions vanishingly unlikely, but it also means UUIDs don't sort chronologically the way an auto-incrementing ID does.

Q: Can I use a UUID as a database primary key?
A: Yes, and it's common. The trade-off is that random UUIDs scatter writes across an index, which can hurt insert performance on very large tables compared with sequential keys.

Q: Is a UUID safe to expose publicly?
A: Yes, in the sense that it can't be guessed. It isn't a secret or an access token though - never rely on a UUID being unguessable as your only protection.

Q: Are UUIDs guaranteed to be unique?
A: Not mathematically guaranteed, but the probability of a collision is so small it can be treated as impossible for any realistic number of IDs.

Sources: Universally unique identifier - Wikipedia (https://en.wikipedia.org/wiki/Universally_unique_identifier); Crypto: randomUUID() method - MDN (https://developer.mozilla.org/en-US/docs/Web/API/Crypto/randomUUID)

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