Linux · Office
Ocular
Okular is KDE’s universal document viewer for PDFs and many other formats.
What is Ocular?
Okular started as part of the KDE project in 2004, evolving from earlier KDE viewers. Over the years it added support for a wide range of file types, annotations, and export options, making it a mature tool for reading and marking documents.
It’s aimed at users who need a single application to handle PDFs, PostScript, DjVu, ePub, and more, without the bloat of a full office suite. The interface is clean, with a toolbar that adapts to the document type.
Compared to Adobe Reader or Sumatra PDF, Okular feels more feature‑rich but still lightweight. It offers annotation tools, form filling, and a built‑in search, while keeping the performance close to Sumatra’s speed.
Best for: Users who need a single, feature‑rich viewer for multiple document types on Linux.
Key features of Ocular
- Supports PDF, PostScript, DjVu, ePub, XPS, and many others
- Built‑in annotation tools (highlight, underline, note, shape)
- Form filling and field editing
- Full-text search with incremental results
- Bookmarks and table of contents navigation
- Export annotations to PDF
- Customizable keyboard shortcuts
- Integrated with KDE file manager
Pros
- Free and open source
- Wide format support
- Annotation and form features
- Good integration with KDE
- Active community
Cons
- Not as fast as Sumatra for very large PDFs
- Some advanced PDF features (e.g., DRM) may not work
- Learning curve for advanced annotation options
Windows programs Ocular replaces
Sumatra PDFTips for Windows users
If you’re moving from Adobe Reader or Sumatra PDF, you’ll find that Okular opens the same PDF files without any conversion. Annotations made in Okular can be exported back to PDF, preserving your highlights. Keyboard shortcuts differ: for example, Ctrl+Z undoes, Ctrl+Y redoes, and Ctrl+Shift+S saves annotations. The toolbar changes based on the file type, so you may need to explore the menu for specific actions like form filling or printing. File formats are the same, so no extra steps are required to open or save documents.
Ocular: frequently asked questions
Does Okular support PDF forms?
Yes, it can fill and edit PDF form fields, though some complex forms may not render perfectly.
Can I annotate PDFs in Okular?
Yes, you can highlight, underline, add notes, and draw shapes, then export the annotations back to the PDF.
Is Okular available on all Linux distributions?
It is included in the official repositories of most major distributions, such as Ubuntu, Fedora, and Arch.
How do I update Okular?
Use your distribution’s package manager; for example, sudo apt update && sudo apt upgrade okular on Debian‑based systems.
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