Okular Overview
Okular is a free, open-source universal document viewer from the KDE project for Windows and Linux, capable of displaying a wide range of formats from a single application. Beyond PDF, it opens EPUB, comic books (CBZ/CBR), images, and other formats, and it provides useful reading and review tools: annotations and highlighting, bookmarks, text selection and search, and the ability to fill in PDF forms. Its annotations can be saved and shared, and it supports a presentation mode for documents. As part of KDE, it is a capable, no-cost reader especially popular on Linux but also available on Windows. It can also read documents aloud with text-to-speech and extract text or images from a page for reuse. This page links straight to KDE's official Okular source.