Skim-app shines in its simplicity, intuitive user interface and its layout of the screen. I miss the possibility of sorting bookmarks, and of the possibility of starting up the app without opening any files, using a key at startup – the function though, is implemented using settings. You will probably encounter such impingements from Apple in the future also – beware of the urge for updating your computer system. Skim offers you the possibility to synchronize the source TeX file with the PDF document, as long as both Skim and the TeX editor know about one another.
I have experienced serious troubles with this app, caused by the lackluster implementation from Apple, of the underlying PDF-things which this app relies on. Skim-app assists in comprehensive and deep reading.
Skim-app ought to be mandatory in any curriculum, and a part of the software library of any public school or university. Though the skim-app is free, it is still better than anything else I have tested, on macOS, Windows, and iOS. Skim-app is an excellent free PDF reading and note taking software, for the macOS.
