The KDE Community have developed a ton of high-quality applications for different needs. Here are some of the best KDE Plasma applications you should try.
One of the new applications introduced with KDE 4 was Okular. KDE 3 had a PDF viewer named KPDF, but Okular aims to be a complete document viewing solution, supporting many different file types. Okular is fast-loading and works in any operating system and desktop environment that can run KDE applications.