GnuPG.com

The Project

The GnuPG crypto engine is an Open Source project. It has its own website at https://www.gnupg.org.

The Windows port

The Windows installer includes the standard GnuPG engine as well as several desktop tools including a plugin for Outlook. See https://www.gpg4win.org for more.

g10 Code and Intevation

These two companies are the main driving force behind the development of GnuPG and Gpg4win and offer third level support.