NxFilter is a security and privacy application that provides robust network protection for businesses and organizations. It is a highly effective content filtering and network security solution that enables organizations to control and monitor their network traffic, providing users with the ability to block websites, applications, and other online content that may be inappropriate or dangerous. NxFilter also provides advanced features such as web threat protection, antivirus and malware scanning, bandwidth control, data loss prevention, and more. By using NxFilter, organizations can ensure their network is secure and their users are safe from online threats.
Discontinued Last updated in 2012: https://sourceforge.net/projects/dansguardian/files/
OpenNIC is an alternative DNS DNS provider, not a DNS filter.