MobileFence - Parental controls for Android devices.
Qustodio - Free parental control software. Monitor and track your child's online activity. Block dangerous sites and protect kids from online bullying.
Boomerang Parental Control - Boomerang Parental Control helps parents start conversations with their children's technology use: App Controls, Text Monitoring, Time Limits and more.
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.
K9 Web Protection - This also contains the feature “Blacklist Without Password” which allows non-admin users to add sites to the “Always Block” list without requiring the K9 admin password.
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.