Casilla 1.2.4 for Mac was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free software for Mac is Suji. Casilla for Mac lies within System Tools, more precisely System Optimization. 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.
From the developer:
Casilla is a simple application that hides and reveals all running applications. Note that the windows are not minimized to the dock, but completely hidden from the workspaces. ll you need to do in order to hide and reveal the opened windows on your desktop is click the app's icon.
You may want to check out more software for Mac, such as Startup Chime Stopper or Dream Day Wedding Married in Manhattan, which might be related to Casilla.