BIND - BIND is by far the most widely used DNS software on the Internet.
Microsoft BitLocker - BitLocker is a full disk encryption feature included with Windows Vista and later.
Knot DNS - High-performance authoritative-only DNS server
Paubox - Paubox provides HIPAA compliant email encryption without the hassle of extra steps.
PowerDNS - PowerDNS offers open source DNS software, services, and support.
OpenSSH - OpenSSH is a free version of the SSH connectivity tools that technical users rely on.