Ervins, Thanks for your review and for alerting us to the seemingly useful, and possibly great security apps at the developers site‼️ After I test them (there are 10 programs), I will review them here.
In reading his notes and 'readme' files for each app, Patrick conveys a real concern with security; not like some who hype their products as ‘the last word’ in Mac security. This developer points out what he sees as both strengths AND weaknesses with his apps –– and his desire to improve them all as he moves forward. Very impressive array of programs and extremely detailed infos on all of his apps.
“OS X malware and security has been a personal passion for many years. However the more I learned about this topic, the more insecure I felt. Malware for OS X is trivial to write and unfortunately has become ever more pervasive. And, using attacks such as dylib hijacking attackers can easily bypass all current OS X security products.
As an avid Mac user, this worried me, so I decided to do something about it. Initially, this was for somewhat 'selfish' reasons; I simply wanted to write OS X security tools to secure my Mac. But then I thought, 'hey, sharing is caring, I should make my tools publicly available, free of charge.' This is the idea that drives the website.”
Patrick Wardle
Not to be missed, is his site’s Blog, where you will find an amazing trove of Mac security information, resources and a detailed overview of the ‘Mac malware’ culture we now find ourselves confronted with.
And as you pointed out –– he has a big heart when it comes to pricing :-)
He very quietly points out (at the very bottom of his site pages), that donations are welcome; but nothing is ‘crippled’
Nice find.
Annie

If they have access to the computer with the same
user or Admin account that you do, change it.
Otherwise, they can use any software you can.
A different user account for them, with a login
and other parameters, limited privileges and
access to the system and internet limited, is
about all you can do.
There are some children-protective browsers;
those could be installed on a child's account.
see - ' mac os x children's software web browsers ' - google search:
http://www.google.com/#hl=en&q=macos+x+children%27s+software+webbrowsers&aq=f&aqi=&fp=azWfBBCvguA
You can also use most browsers to not allow content
from specific sites by URL; that control would depend
on the browser(s) in use and how they are set up.
The separate accounts for other users, where
you would also have to log-in to use the Mac,
would be a better idea overall; and then you
can limit access to the hard disk drive, and
the applications, and give them a limited access
and a few items in the Dock. And kid browsers.
This could also save you a lot of trouble should
someone decide to mess with the System or a
few of your important files on the hard drive. It
also would enhance overall security on the Mac.
Good luck & happy computing! 🙂