Archives For November 30, 1999

Looking for an app to sign, annotate, or edit PDF files in Ubuntu Linux? Here I’m going to introduce some for you!

PDF, stands for Portable Document Format, is a file format that’s popular for office use. Besides using Adobe Acrobat, Linux has quite a few applications that can edit this file format.

1. Firefox

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OnlyOffice, the popular free open-source office suite, announced new 8.1 release for its desktop editors.

The Desktop Editors is the offline use version of OnlyOffice office suite. It’s made up of Document, Spreadsheet, Presentation, and PDF Form apps, and, supports collaborative editing by connecting to a cloud service.

The new 8.1 release finally added full-featured PDF editing support for the both online and offline apps. After opened a PDF file, go to Home -> Edit PDF to toggle between viewing and editing mode.

When in editing PDF mode, you’ll see the tool-bar options to edit text, add, rotate and delete pages, insert various objects, such as text boxes, shapes, images, hyperlinks, tables, and more.

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For those want to unlock / decrypt PDF files, there’s now a stupid simple graphical tool to do the job in Linux.

It’s easy to encrypt you PDF files in Ubuntu Linux since the built-in LibreOffice office suite has the option on ‘Export as PDF’ dialog. However, there seems no easy way to remove password for PDF file, other than using qpdf command:

qpdf --decrypt --password=<PASSWORD> input.pdf output.pdf

unlockR is a new GTK4 application that use Libadwaita to provide a modern simple user interface to decrypt your PDF files.

It’s so simple that you just need to click ‘Open a File‘ to select your PDF, then type the password, and finally hit ‘Decrypt’. It doesn’t change the original file, but generates a new PDF without password protect.

As the picture shows, it has both light and dark mode that switches automatically according your system color scheme.

NOTE: This app is NOT about to crack password on a PDF file. You need the password to be able to decrypt it.

How to Install unlockR

It is a free open-software software works on both Linux and Windows. For Windows package, just grab the zip from github releases page:

For Linux, it offers the binary package via universal Flatpak. Ubuntu user need to first press Ctrl+Alt+T on keyboard to open terminal, and run command to install the Flatpak daemon:

sudo apt install flatpak

Next, install the app package via command:

flatpak install

Like normal applications, search for and open it from ‘Activities’ overview (or start menu) after installation.


To remove the Flatpak package, open terminal and run command:

flatpak uninstall --delete-data com.github.jkotra.unlockr

You may also clear useless runtime libraries via flatpak uninstall --unused.

Working with PDF files regularly in Ubuntu Linux? QPDF Tools is a nifty tool to manage your PDF documents.

It’s a free and open-source software, easy to use Qt based user interface for Ghostscript and Stapler, with ability to compress, split, merge and rotate your pdf documents.

The main window is simple and works with 4 buttons. Click the action you want to do for the PDF documents. Then select the PDF along with a few options and click the button to go.

The Compress a PDF file option will change the resolution for printing, Ebooks, or screen optimized. It also reduce the file size depends on the option you choose.

It however may stuck a few seconds when you clicking ‘Save‘ button on exporting file dialog.

While ‘Merge PDF files‘ option allows to add multiple PDF files, arrange them, and convert them into single, the ‘Spile a PDF file‘ option allows to extract all PDF pages or export from one page to another. And ‘Rotate a PDF file‘ can rotate left or right with live preview.

How to Install QPDF Tools:

The DEB package for Ubuntu, Debian, Linux Mint, as well as the source tarball are available to download at the link below:

The software developer also maintains an Ubuntu PPA that support all current releases, e.g., Ubuntu 18.04, Ubuntu 20.04, Ubuntu 20.10, and Ubuntu 21.04. The packages for old releases, e.g., Ubuntu 12.04, Ubuntu 14.04, and Ubuntu 16.04 are also available.

1.) Open terminal from system app launcher. When it opens, run command to add the PPA:

sudo add-apt-repository ppa:silash35/qpdftools

2.) Then refresh package cache (optional for Ubuntu 20.04 & higher) and install the tool via commands:

sudo apt update
sudo apt install qpdftools

Once installed, open the tool from your system application launcher and enjoy!

Uninstall QPDF Tools

While the Ubuntu PPA is used to install or upgrade the software package, you can safely remove it either by running command in terminal:

sudo add-apt-repository --remove ppa:silash35/qpdftools

Or by going to ‘Software & Updates’ -> ‘Other Software’, and remove the relevant line.

To remove the software, either use Synaptic Package Manager or run command:

sudo apt remove --purge qpdftools