Is this UUID safe to use as a database primary key?

Yes. UUID v4 has 122 random bits (the other 6 are version and variant flags). Generating a duplicate has a probability low enough to be considered zero in practice (the birthday-paradox math predicts a collision after ~2^61 IDs, more than humanity will ever need). MongoDB, PostgreSQL, MySQL, and most modern databases accept UUIDs directly.

Where does the randomness come from?

The browser's built-in cryptographically secure random number generator (the Web Crypto API), seeded from the OS entropy pool. NOT `Math.random` (which is predictable and unsuitable for security). The output is suitable for security tokens, session IDs, and any context where unpredictability matters.

Are UUID v4 and v7 different? Should I care?

Yes. v4 is fully random and unsortable. v7 (newer, RFC 9562) embeds a millisecond timestamp at the front, so newly created UUIDs sort roughly in the order they were generated, which helps database index locality. This tool generates v4 (universal support). For v7 you would need a dedicated library.

Why are some UUIDs lowercase and others uppercase?

Hex characters in UUIDs are case-insensitive per RFC, but conventions vary. JavaScript and most modern systems output lowercase. Older Microsoft tools (regsvr32, GUID picker) output uppercase. Both refer to the same value. Some pipelines compare strings strictly, so pick a style and stick to it.

Where is the UUID generated?

Entirely in your browser via the Web Crypto API. Nothing leaves your device. For password generation use Password Generator.

Free, no signup, no rate limit (everything runs client-side).

Utility

UUID Generator

Generate UUIDs

Input

Generate collision-free UUID v4 identifiers. Statistically unique and safe for database keys.

Terminal

Console ready. Execute a command to see output...

About UUID Generator

Universally Unique

A UUID (Universally Unique Identifier) is a 128-bit number. The probability of generating a duplicate is so astronomically low that for all practical purposes, it is zero.

Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

Use Cases

Database Keys: Distributing ID generation across millions of servers without coordination or collisions.
Session IDs: Tracking users without revealing personal info.
Filenames: Preventing file overwrite in cloud storage.

How to use UUID Generator

Hit Generate UUID
A single UUID v4 appears in the terminal panel.
Or Generate 5
Same button family but emits five UUIDs at once for batch use.
Copy the value
Click and copy from the terminal panel. UUIDs never leave the browser, so nothing logs them on the server side.

Frequently Asked Questions

: Yes. UUID v4 has 122 random bits (the other 6 are version and variant flags). Generating a duplicate has a probability low enough to be considered zero in practice (the birthday-paradox math predicts a collision after ~2^61 IDs, more than humanity will ever need). MongoDB, PostgreSQL, MySQL, and most modern databases accept UUIDs directly.
: The browser's built-in cryptographically secure random number generator (the Web Crypto API), seeded from the OS entropy pool. NOT Math.random (which is predictable and unsuitable for security). The output is suitable for security tokens, session IDs, and any context where unpredictability matters.
: Yes. v4 is fully random and unsortable. v7 (newer, RFC 9562) embeds a millisecond timestamp at the front, so newly created UUIDs sort roughly in the order they were generated, which helps database index locality. This tool generates v4 (universal support). For v7 you would need a dedicated library.
: Hex characters in UUIDs are case-insensitive per RFC, but conventions vary. JavaScript and most modern systems output lowercase. Older Microsoft tools (regsvr32, GUID picker) output uppercase. Both refer to the same value. Some pipelines compare strings strictly, so pick a style and stick to it.
: Entirely in your browser via the Web Crypto API. Nothing leaves your device. For password generation use Password Generator.
: Free, no signup, no rate limit (everything runs client-side).