NxFilter is a free web filter designed to monitor and filter Internet activity in an enterprise environment.

You can also protect users from malware and botnets, while enjoying many useful features. These features include local DNS caching to accelerate Internet speed, load balancing and cluster fault protection, Active Directory integration support, user / group-based policy allocation, remote user filtering, bandwidth control, phishing protection, malware and botnet detection, and time quotas.
The publisher’s web link:https://www.nxfilter.org