If you are looking for an open-source PDF viewer and editor, then this is for you. Okular is a free and open source document viewer foe Linux, Windows and MacOS. It supports PDF, EPub, DjVU and Markdown, JPEG, PNG, GIF, Tiff, WebP, CBR, CBZ and many more file formats. It comes with build-in annotation mode features like adding text, inline notes, popup notes, highlight text, underline text, or even add your own text.
It also comes with select and view any text, thumbnails navigating panel, view and verify digital signatures embedded in PDFs. It is a kde project and released under GNU General Public License v2.0 or later.
How to Install Okular on Ubuntu Linux
You can install Okular via apt, snap and flatpak. Open your terminal software using ctrl+alt+t keys and run below Okular install command. It will install the latest version of Okular pdf viewer application on your Ubuntu Linux system.
sudo apt install okular
Now you can open it via the applications menu or via below command.
Install Okular via Snap:
In the terminal application run this Okular snap install command.
sudo snap install okular
You can uninstall Okular via below command.
sudo snap remove okular
Install Okular via Flatapk:
If you don’t have flatpak and flathub, then install flatpak and flathub and restart your system after the installation . Now in the terminal software run below Okular flatpak installation command.
flatpak install flathub org.kde.okular
After the installation you can run Okular using
flatpak run org.kde.okular
and Uninstall okular using
sudo flatpak uninstall org.kde.okular