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These are alternatives to Microsoft Defender Anti-Virus that are free.
It's just an opinion and you may have other preferences. I have used Avast and AVG and they are pretty decent especially for free software. Norton has been pretty consitently good. There are others that are just fine as well. Honestly at this point Microsoft Anti-Virus and Firewall is very good at this point. I don't remove it or worry about it if somone has it and likes it.
On the other hand I especially dislike McAfee. If somone is using them and they like it it's nominally acceptable. It's really not better than Microsoft choices and agruably much worse.
Most importantly - I prefer people use something they like and keep everything updated.
Good Anti-Virus. I have used this one.
Updates frequently (several time a day at times) but doesn't interfere with your work.
Ability to scan all files before bootup is useful. Now has an annoying tendency for pop-ups.
Several friends use this and I concur - good anti-virus software.
Another one several friends use. It's good but I prefer others. HOWEVER, can be useful on older computers as it is lighter on resources.
I find the firewall in Windows to be quite acceptable for most situations.
There are good aftermarket ones you may wish to try.
I used to use the ZoneLab firewall. In time it was renamed. It worked well when I used it but I haven't used ZoneAlarm. I expect it is fine.
Used this too but it has been some time now.