On this page you can see a comparison between free programs. To compare free and paid programs, to read about what to look for at a parental monitoring software go to this page.
There are very good and free programs made for parents who want to control the children when they are surfing the internet, by preventing the access to different categories of websites (adult, gambling, racism etc.).
Qustodio is a free application available for different devices and once is installed, you will start to receive reports in your online account. The program can block the access to different categories of websites, you can view a list with programs used and visited websites, then take action. From your online dashboard, you can block or allow entire categories with websites with a single click. Also, you can set time limits for internet access.
They have a premium version for geolocation and calls/SMS tracking, useful for mobile devices.
Norton Family is similar with Qustodio regarding free features. It blocks instantly the access to forbidden categories of websites, is displays reports with visited websites and keywords used in search engines. You can manage the settings and view reports from anywhere, through your online account.
Also, they have a premium version to track location, calls and SMS on mobile devices.
Kurupira Web Filter is a completely free program, without any paid upgrades, but you can access it and manage settings only on the device where is installed. Is focused to block the access to adult websites, but you can add your own URLs. It displays detailed charts and reports. You can block the access to applications and set time limits for the internet access.
K9 Web Protection is also a free program able to block different categories of websites. is available for multiple devices and you can manage settings only from the device where is installed.