Kryptomate

A free and ad-free open-source app you can use to encrypt or decrypt text using Caesar or Vigenère methods that contentrates on having a simple, self-explaining and nice interface.
This app requires no permissions and will not save any data to your memory.

This app was created more for fun and I know it has limited use, nevertheless I found it surprisingly useful more than once.
Feedback, especially bug reports and feature requests are very welcome.
The whole source code of this program is available in a git repository at https://github.com/sjm1835/Kryptomate . Feel free to fork it, change it and file pull requests :)