Okular: Universal Document Viewer For KDE 4

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.

Document Types

Out of the box, Okular can view a plethora of document types, including:

PDF – used for a variety of documents
PS – Postscript print documents
TIFF – often used for faxes
CHM – help files, ebooks, and online documentation
DjVu – scanned documents
Images – JPEG, PNG, and many more
DVI – device independent file format
XPS – windows printing specification
ODT – Open Document Text (for reading, not editing)
Fb2 – fiction book file format for eBooks
CBZ, CBR – comic book archive
Plucker – eBook format
Epub – free and open eBook standard
Fax – file format for faxes

Okular comic book viewer


Okular has many of the standard PDF viewer features like page navigation, table of contents, browsing, zooming, text selection, and bookmarking. In addition, it also offers users the ability to annotate documents, highlight important information, have the computer read the entire document using text-to-speech technology, save annotated documents, view embedded files, listen to sounds and movies, fill out forms, search documents, and read DRM encrypted files.


Okular has four modes for viewing and manipulating documents:

1. Browse (Ctrl+1) – Clicking on the document allows you to drag the page up, down, left, or right.

2. Zoom (Ctrl+2) – Click and highlight an area to zoom in on it.

3. Selection Tool (Ctrl+3) – It uses a selection box to highlight any area and can copy images or text.

4. Text Selection Tool (Ctrl+4) – This functions more like a text editor’s selection tool, highlighting text, row-by-row.

To search a document, press “Ctrl+F” and enter the text you wish to find. The search tool will begin searching from the moment you start typing. It will highlight each occurrence of the text and give you the ability to navigate through them.

To start making annotations, press F6. A small vertical toolbar with each type of annotation will appear. They can take any of nine forms: note, inline note, green freehand line, yellow highlighter, straight yellow line, blue polygon, stamp, black underlining, and cyan eclipse.

Okular highlighting and notes

There are four view modes for Okular, found in the View menu:

  1. Single page – scrolls one page at a time
  2. Facing pages – displays two pages, side-by-side
  3. Facing pages (center first page) – like normal facing pages, but displays the first page by itself, which is useful if the first page is a book cover.
  4. Overview – which shows three zoomed-out pages at a time.

Also included in the view menu is the ability to rotate the document, trim the margins, and use the document as a presentation. By clicking presentation, the document becomes fullscreen, and the user can navigate through the pages just like a PowerPoint slideshow. When in presentation mode, a dial in the top right with a number in the center keeps track of the number of pages viewed.

Universal Viewer

Because of Okular’s versatility, you can use it to view any document, eBook, fax, or image quickly, easily, and safely. Okular is light enough to be portable and work well even on tablets and small devices, but it is also powerful enough to view very large, complex documents as well. Okular is part of KDE and is free and open source software, available to everyone.

Tavis J. Hampton

Tavis J. Hampton is a freelance writer from Indianapolis. He is an avid user of free and open source software and strongly believes that software and knowledge should be free and accessible to all people. He enjoys reading, writing, teaching, spending time with his family, and playing with gadgets.

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