On the one hand, I can say that yes, free proxies can be good. But not all of them. Because often free proxies are used by a large number of people, which makes them slow down in work, not always provide maximum protection and security. Well it again depends on which proxies you choose. Here, for example, is a list of really reliable free online proxy that you can use for any purpose https://floppydata.com/free-proxy/.