Website, DB, & Software Developers

...and it is essentially uncrackable if used only once.

The problem for online use is this: both parties need the key. Therefore, you need a secure way to send the key before sending the enciphered message. But the key for a one-time pad is the same length as the message, so if you have a secure way to send the key, you may as well just use it to send the message in the first place.

That is why public key encryption is the gold standard for online encryption. The protocols using public and private keys allow secure key exchange even over public channels. If the key values are large enough, this is also essentially uncrackable, assuming you are using software and hardware without any back doors...