Download Skim 1.6.9 (Mac) – Download Free

The Preview app, a built-in utility for macOS, can open PDF documents and even includes basic annotation tools: you can underline text, add text boxes, thought bubbles, and more.

skim is an open source project that includes all these basic PDF management features, but also supports the use of AppleScript, Apple Remote Control, LaTeX, SyncTeX, BibDesk, and more.

Simplified PDF viewer and annotator with an intuitive interface

The main browse window is only visible when working with documents, so you must start by opening a PDF file. Skim allows you to quickly browse files by viewing page thumbnails or table of contents, while the central area is reserved for visualizing PDF content. Meanwhile, Skim has a third panel that displays your notes in list mode.

For convenience, the top area of ​​the Skim main window provides navigation buttons and annotation tools: their icons and names are mostly self-explanatory (hover over the top of each icon to see the tool name).

Seamlessly synchronize changes in PDF documents with TeX source files

The Skim Preferences window allows you to adjust general details about the appearance of the application, such as display appearance or default annotation colors. On top of that, in the sync panel you can easily enable the “Check file changes” feature and choose a PDF-TeX sync preset.

Skim lets you synchronize source TeX files with PDF documents as long as Skim and the TeX editor know each other. By default, Skim works with popular TeX editors such as TextMate, BBEdit, LyX, TeXMaker or MacVim, but you can also create your own custom presets.

Versatile solution for viewing and annotating PDF documents while synchronizing them with source TeX files

All in all, Skim provides a clean and organized environment for performing basic PDF annotation tasks: the application’s main window provides quick access to most tools, and you can easily find your way.

It is also worth noting that Skim also has a PDF-TeX Sync function, which allows you to visualize the source TeX code corresponding to a line in a PDF document.