Downloading OneTimePad 1.2 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. The application is included in Security Tools. The actual developer of this free software for Mac is Landon Manning.
From the developer:
This application is a very simple one time pad. This pad allows you to input a message and a key (if no key, it will generate one which is NOT SECURE) and outputs the encrypted message. Conversely, you can also input a cryptographic message and a key to decode the message.
You may want to check out more software for Mac, such as Key Holder or PasswordVault Lite, which might be related to OneTimePad.