D7 provides a collection of PC tweaks and tools that can help you optimise your PC, repair problems, remove malware and more.
The program is portable, and the author's intention is that you'll combine it with many other free tools to build your own troubleshooting toolkit. Click the Malware tab, for instance, and you'll see buttons to launch programs like Malwarebytes and AutoRuns. However, you'll need to manually download these and copy them to D7's own folder before these will work.
D7 does include plenty of tools of its own, though. So there are options to carry out offline Registry editing, for instance. A "DataGrab" function allows you to collect the data you need from the current system. And there are modules to carry out CPU and RAM stress testing, a Tweaks section with various Windows tweaks, a set of Repair tools to, say, repair and reset the Windows firewall, and various other features.
Some of these features appear useful, but others are less obvious, and there's little documentation to help you figure out what you're doing. You need to be extremely careful, then, as the author himself spells out:
"THIS TOOL IS INTENDED FOR EXPERIENCED PC TECHNICIANS ONLY, NOT FOR "END USERS." This tool can be very dangerous and destructive in the wrong hands, or even in the right ones. I have personally even hosed my own development machine by accidentally clicking the wrong button. Sometimes I don't fully *test* D7 prior to use. So you are forewarned! If you are concerned about your data or the well being of your computer, then please make a backup of everything important prior to using D7. "