Adblock Plus - AdBlock Plus is a browser extension for Firefox, Chrome, Opera, and several other popular browsers that prevents intrusive ads like pop-ups and malicious code from appearing on websites you visit.
CurrentWare BrowseControl - BrowseControl web filtering software blocks websites based on URLs and categories. Policies can be customized for each user, department, or OU. Includes other features such as an app blocker, port filter, and download/upload blocker.
uBlock Origin - Popular and efficient blocker for Chromium, Chrome, Edge, Firefox, Opera, Safari, Thunderbird.
Qustodio - Free parental control software. Monitor and track your child's online activity. Block dangerous sites and protect kids from online bullying.
AdGuard - Surf the Web Ad-Free and Safely. Shield up!
NxFilter - Best performance. You don't want to slow down your network by installing a network security software. NxFilter is a light-weight DNS filter. It doesn't cause any latency issue in your network.