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).
Seahorse - Front end for GnuPG.
GPG Suite - Use GPG Suite to encrypt, decrypt, sign and verify files or messages.
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.
VeraCrypt - VeraCrypt is a free open source disk encryption software for Windows, Mac OSX and Linux.