Kleopatra

Gpg4win (GNU Privacy Guard for Windows) is "encryption software for files and emails," supporting both OpenPGP and S/MIME.

• Licensing: GNU General Public License (GPL) v2.0 (Source code)

It contains Kleopatra, a certificate manager for OpenPGP and X.509 certificates.

• Licensing: GNU General Public License (GPL) v2.0 or later (Source code)