Mac: Diagnostics utilities don't really need to be feature-packed. In fact, since their main purpose is to give you information about a busted Mac, it's best if they're very simple. EtreCheck fits that bill.
EtreCheck collects a lot of statistics about your Mac. This includes your hardware, software, installed apps, kernel extensions and just about anything else that can cause your Mac to stop working. When it's done collecting information, EtreCheck gives you a simple, text-based report so you can easily send that info to someone for help (or troubleshoot your own computer). It's a super-easy way to figure out what's going on with your Mac without running any complex utilities.