GPGshell is described as 'Windows GUI for the GNU Privacy Guard - an open source software suite for public-key cryptography compatible with PGP. It provides a simple-ish interface to manage the encryption keys, encrypt and sign files, check the signatures and the like'. There are eight alternatives to GPGshell for a variety of platforms, including Windows, Android, iPhone, iPad and Android Tablet. The best alternative is GPG4Win, which is both free and Open Source. Other great apps like GPGshell are GPGTools (Freemium, Open Source), p=p (Free, Open Source), gpg4usb (Free, Open Source) and WinGPG (Free, Open Source).
Gpg4win enables users to securely transport emails and files with the help of encryption and digital signatures. Encryption protects the contents against an unwanted party reading it. Digital signatures make sure that it was not modified and comes from a specific sender.
It offers an automatic and easy to use solution with end-to-end protection for all written digital communications over the Internet. It have been designed to provide extremely easy and automatic encryption by default for e-mail.
A GnuPG Frontend GUI made in C#. It is compatible with PGP as well so it can be a very useful tool for encryption/decryption. It also incorporates a shell extension so it can be easy to right click and decrypt or decrypt.
Desktop Email Encryption provides an end-to-end email encryption solution that automatically encrypts and decrypts email directly from one user's client to another's without the need to log into a third-party website or by other means.