For scanning and basic threat protection, yes but you don’t get the bells and whistles. The paid versions offer extra detection engines which will cover threats like ransomware and bitcoin miners. they'll also provide notifications of huge account hacks and check to ascertain if your email addresses are exposure on “dark web” sites. That said, Windows Defender is free, is already included with all Windows versions from 7 on, and is backed by the huge resources of Microsoft and its technical teams. I even have used nothing but Pcunif on my Windows PCs (and on friends and family’s PCs) for years now with excellent results.