The GNU Privacy Guard (GnuPG) is a free replacement for PGP.

PGP® or Pretty Good Privacy® is a powerful cryptographic product family that enables people to securely exchange messages, and to secure files, disk volumes and network connections with both privacy and strong authentication.

Reviews of Macintosh specific PGP applications.

Cryptocx is an encryption control that has full PGP support. You can use PGP keys to encrypt/decrypt strings and files from within your applications or ASP sites.

Source of OpenPGP (RFC 2440) software for multiple platforms - Windows, Unix, OS/400 and zOS.

Products and Technologies for OpenPGP and S/MIME integration for corporate use. Advanced client products for Microsoft Outlook, Lotus Notes, Hard Disk Encryption and others. PKI Technology for CA/RA integration of PGP and X.509.

Free components providing encoding, decoding and several key management functions for Delphi versions.

Develops and supports ZENDIT simple to use public key technology for encryption, digital signatures, and digital identity software that is compliant with the OpenPGP standard. Authora is a founding member of the Open PGP Alliance.

Secure email using PGP 5 or 6, and also one-way anonymous (recipient cannot reply) and two-way anonymous (recipient can reply, but not trace who you are) remailing.

Authora is dedicated to promoting the use of PGP worldwide. The Authora SoveriegnSuite includes ZENDIT, for digital signing, encrypting and access control. ZENDIT can also integrate X.509 Certificates.