First off, this is a good thing to ask. A more specific approach is, "what's safe about them, and what's unsafe about them" and you have to think about this in terms of what you're trying to protect yourself from. So there's the idea of **who** you are concerned about, this can be - Hackers, with various motivations - Your ISP - Other internet infrastructure orgs - Whoever runs the platform in question - Your device/operating system provider/manufacturer - Copyright holding groups - Your school or employer - Law enforcement - Other government agencies - Other countries governments - Political activist groups - Family, friends, aquaintances - Other users of the platform - this list could go on You basically have to look at each one that matters in the context of why you're concerned about safety. Pirating movies for example? Main thing is to make sure the traffic is not clear to your isp and keep copyright holders from knowing an IP address that can be tied to you. Racist talk and don't want to get doxed? The platform owners themselves must be both willing and able to resist political activist groups, and not expose information that can link back to you. People made this mistake with discord over and over for example. Fedposting with intent? You need to evaluate for every layer on that list. It's basically a whole project to determine safety specifically for each use-case. You can't really rely on a blanket answer. And also you need to keep in mind that things can change, and be ready for that when it happens. I know this is probably a frustrating answer but it's the right way to approach it. If anyone knows of detailed security assessments that allows commenting and updates for any of these platforms that's basically the way to go about this. Like I said it's a whole project to figure this out for each use case.