Kleopatra - Kleopatra is a certificate manager and GUI for GnuPG.
GnuPG - GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP).
YAATA - YAATA app offers features that let you send multimedia files such as images, videos, audio, and GIFs, etc.
GPG Suite - Use GPG Suite to encrypt, decrypt, sign and verify files or messages.
Enigmail - Security extension to Mozilla Thunderbird and SeaMonkey
GPG4Win - GPG4Win is an encryption program for files and emails. The program encrypts emails and files so that they can only be read by those intended to receive them.