This beautiful app will show you all the forgotten files that are slowing down your Mac

Computers have transformed our desks - and not necessarily for the better.

Where previously workers had great stacks of paper and overflowing filing cabinets surrounding them, many offices are now going completely paper-free.

But replacing this clutter is near-infinite quantities of digital junk: Thousands of virtual folders containing every file you ever forgot you downloaded, quietly taking up space.

Three years-worth of old expense reports? Obsolete induction guides for offices you no longer work in? That hour-long video of the disastrous company all-hands meeting last year? It's all in your laptop somewhere, almost impossible to find and delete.

Luckily, there are apps out there that are a godsend for helping you map your hard drive so you can figure out what's taking up so much space. My favourite for Macs running OS X is called GrandPerspective, and it's free to download and use.

Here's how it works.