The 1.0 version of Pulvinus for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The application lies within System Tools, more precisely System Optimization. We recommend checking the downloaded files with any free antivirus. This free Mac app is a product of Tim Hagemann.
From the developer:
Pulvinus is a disk space analyzer that uses a visualization technique called squarified cushion tree maps to show in a very intuitive manner the files on your disk using most of the space. The app features a customizable color-coding mechanism for file types to make it even easier for you to identify your directories and files.
You may want to check out more software for Mac, such as TrashMagic or WebGrab-FF2, which might be related to Pulvinus.