Download of Gridus 1.3.1 for Mac was available from 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 Design & Photo Tools, more precisely Viewers & Editors. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This software for Mac OS X was originally developed by UrbanFort LLC.
From the developer:
Using Gridus you can quickly build perspective grids and other utilities for drawing or design. The application helps artists be more productive by allowing them to create dedicated perspective grids for use in their illustrations without locking them into a single drawing application.
You may want to check out more Mac applications, such as Resize Now, which might be related to Gridus.