Zeal is a very handy tool for accessing various APIs and other reference documents. However, if you want to run it on macOS, you’ll have to compile it yourself (long story). Here’s how I got it running on macOS High Sierra.
Install MacPorts (Homebrew would probably be similar, but MacPorts is what I use). You’ll also have to install XCode; see the MacPorts site for more on this (you most likely have already installed XCode if you’re planning on using Zeal).
Install required packages:
% sudo port install qt5 qt5-qtwebkit qt5-sqlite-plugin libarchive
Get Zeal sources:
% git clone https://github.com/zealdocs/zeal.git
Here’s the step not outlined anywhere, which I spent quite a while figuring out so you don’t have to: Edit .../zeal/src/CMakeLists.txt and add the following line as the first line (all on one line):
set(CMAKE_LIBRARY_PATH /opt/local/lib ${CMAKE_LIBRARY_PATH})
From here, follow the instructions in .../zeal/README.md to build Zeal. Happy hacking, and like GreatScott! would say, “Stay creative, and I will see you next time!”