While you can't actually delete anything within the main window (and most system files are completely locked away from view), right-clicking on a file or folder tree brings up a menu with options for Get Information, Reveal in Finder, and Quick Look, which I found particularly useful.
As its name suggests, Disk Graph ($2) displays your hard drive's data as an interactive infographic that you can explore and erase with ease. Unlike the other utilities here, it doesn't automatically recognize installed or mounted drives--you'll need to open a volume using a standard navigation window and add it to your favorites to keep it there. But that's a relatively minor inconvenience when you can get up close and personal with every file residing on your drive.
Once it's done scanning--a quick process that routinely finished up before the progress bar's estimate--you'll get the usual sunburst of colored bars. But I found Disk Graph to be a bit more forensic with its scanning, as it catalogued every nook and cranny, right down to the files tucked away in the hidden Library folder. Moving in and out of circles is a breeze, and anything that isn't locked by the system can be deleted without needing to leave the app. And if you're looking for something specific, a handy built-in search bar will cut down on the blind guessing.
No matter how you use your Mac, you'll find that most of your space-clearing sessions focus on the same cluster of files, mostly located in your Home folder. With HD Cleaner ($5) you can quickly access the folders where they're hiding without needing to forage through the fountain of files you probably want to keep.
HD Cleaner is about as lightweight as a disk-scanning app gets. It works exclusively within your Home folder, but each time it launches it will still prompt you to select it, an extra step that seems unnecessary. Thankfully, it takes about as long to run as it does to click Open, and in less than a second you'll have a list of seven folders that you can clear with a single click on each one. Be careful before rushing down to the red delete button, however, as one of the folders it offers to clear is Downloads, which might contain some files you want to keep. It also does a fine job of tracking down any large documents, which are accessible via a slide-out window.
Don't be fooled by the wimpy name: Daisy Disk ($10) is one of the most powerful utilities you're likely to find. With a remarkably intuitive interface that breaks your drive down into easily digestible chunks, Daisy Disk will give you an exhaustive overview of your drive, letting you explore your files in a novel way.
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