This is a Plist (Property List) file viewer that supports two modes: Outline mode and Source Code mode. Why develop this app? Because macOS has many files in Plist (Property List) format, and many apps use this format to store data. This format can be saved either in binary or plain text form. If it's saved in binary form, opening it with a regular text editor will display gibberish, so a specialized app is needed to open it. Although Apple's Xcode can open and edit binary Plist files, downloading several gigabytes of Xcode just for viewing and editing Plist files seems like overkill.
