Clam AntiVirus is an open source (GPL) anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail gateways. It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and advanced tool for automatic database updates. The core of the package is an anti-virus engine available in a form of shared library.

ClamWin Free Antivirus. GNU GPL Free Software Open Source Virus and Spyware Scanner.

ClamAV/SOSDG is a port of the powerful ClamAV anti-virus software package from UNIX/Linux to Windows using the Cygwin compatibility layer. It has been tweaked to the best of our abilities while still maintaing complete compatibility with the original version, allowing unmatched compatibility with other apps that can use ClamAV.

Like the original version, ClamAV/SOSDG is based on the GPL v2 license, which means it is free to download and use provided if you make any changes, that you contribute them back to the community.

Snare for Windows is a Windows NT, Windows 2000, Windows XP, and Windows 2003 compatible service that interacts with the underlying Windows Eventlog subsystem to facilitate remote, real-time transfer of event log information.

Event logs from the Security, Application and System logs, as well as the new DNS, File Replication Service, and Active Directory logs are supported. Log data is converted to text format, and delivered to a remote Snare Server, or to a remote Syslog server with configurable and dynamic facility and priority settings.

GnuPG is the GNU project's complete and free implementation of the OpenPGP standard as defined by RFC2440 . GnuPG allows to encrypt and sign your data and communication, features a versatile key managment system as well as access modules for all kind of public key directories. GnuPG, also known as GPG, is a command line tool with features for easy integration with other applications. A wealth of frontend applications and libraries are available. Version 2 of GnuPG also also provides support for S/MIME.

GnuPG is Free Software (meaning that it respects your freedom). It can be freely used, modified and distributed under the terms of the GNU General Public License .

Privoxy is a web proxy with advanced filtering capabilities for protecting privacy, modifying web page data, managing cookies, controlling access, and removing ads, banners, pop-ups and other obnoxious Internet junk. Privoxy has a very flexible configuration and can be customized to suit individual needs and tastes. Privoxy has application for both stand-alone systems and multi-user networks.

PINs is a free feature-rich Windows program for safe and comfortable storing of any secure information like passwords, accounts, PINs etc. PINs uses a secure 448 bit Blowfish algorithm to ensure the data are not crackable. The password used for securing access to stored data is not saved anywhere.

PINs does not require installation and does not need any special dlls, drivers or system files which can mess up your system. This means that PINs can run directly from floppy - including data files - without installing anything. This is extremely useful if you wish to easily access your data on other computers as well.

PINs is OSI Certified Open Source Software.

GUIDClean is a program to detect, display and modify the Global Unique Identifiers (GUID) that some MS Office products (Word and Excel) place in documents. An argument can be made that these GUID strings are a breach of users' privacy and may be used to track documents and bind them to particular users or particular machines. As author of GUIDClean I make no such arguments: I simply provide you with a free program which you can use to view and/or change the GUID information in your documents.

AxCrypt File Encryption Software - Free Personal Privacy and Security for Windows 98/ME/NT/2K/XP with AES-128 File Encryption, Compression and transparent Decrypt and Open in the original application.

Oubliette gives you a choice of encryption algorithms: Blowfish or Idea. The algorithms were chosen because they are cryptographically strong and free for non-commercial use. (Oubliette uses a great freeware library, DCPCrypt, written by David Barton, that implements the cryptographic algorithms. Please see the FAQ for more details.)
And best of all, Oubliette comes with full source code, so you can inspect the program for any hidden doors (there are none), or modify it to create your own version.