How to Sign a PDF on Linux

1. In the browser (no packages)

The editor above runs in Firefox, Chrome, Chromium, Brave or Vivaldi on any distribution, from a Flatpak or snap browser too.

1. Drag the PDF from your file manager onto Drop your PDF here, or click the box to pick it.
2. Sign on the Draw tab with mouse, touchpad or tablet and click Use This Signature, or switch to Type and pick a handwriting style for your name.
3. Click the signature line on the page. Hover the placed signature to show its resize square and delete button; drag it to adjust.
4. Use Previous/Next for other pages; Add Initials, Add Date and Add Text fill the remaining boxes of the form. Ctrl+Z undoes, Ctrl+Y redoes.
5. Click Confirm & Download Signed PDF; the file is saved as name-signed.pdf. A plan is needed for this last step.

Signatures are embedded as images and form fields you fill in are flattened, so the result looks the same in Evince, Okular, Firefox’s viewer or any other reader.

2. Xournal++ (best with a pen tablet)

Xournal++ is an open-source note-taking and PDF annotation app. Per its README, it is in the official repositories of Debian (bookworm and later), Ubuntu 22.04 and later, Fedora, openSUSE Tumbleweed and Arch, and on Flathub:

sudo apt install xournalpp          # Debian, Ubuntu
sudo dnf install xournalpp          # Fedora
sudo zypper in xournalpp            # openSUSE Tumbleweed
sudo pacman -S xournalpp            # Arch
flatpak install flathub com.github.xournalpp.xournalpp

1. Open the PDF (File → Annotate PDF, or xournalpp file.pdf).
2. Pick the pen, set width and color, and sign on the line, ideally with a tablet.
3. Use File → Export as PDF to write a new PDF with the signature in it. Saving normally creates a .xopp project file instead.

3. LibreOffice Draw (often already installed)

Draw ships with a PDF import filter that can open and edit some PDFs. Open the file in Draw, choose Insert → Image and pick a PNG of your signature (transparent background works best), place and size it, then use File → Export as PDF. The catch: Draw rebuilds the page from the PDF’s contents, so fonts and spacing can shift on complex layouts. Compare the export with the original before you send it.

4. From the terminal with pdftk

If you script your paperwork, pdftk can overlay one PDF on another. Its stamp operation lays the first page of a stamp PDF over every page of the document; multistamp applies stamp page 1 to page 1, page 2 to page 2 and so on. To sign a single page you therefore need a stamp PDF with the same page size and the signature already in the right position:

pdftk contract.pdf multistamp signature-pages.pdf output contract-signed.pdf

Getting the position right is trial and error, which is why most people only use this for repeated, identical forms.

Which method to pick

Common problems on Linux

• Password-protected PDF. The browser editor rejects encrypted files. Remove the password (for example, open the file and print it to a new PDF with your system’s “Print to File” printer) and sign the copy.
• Touchpad signature looks rough. Use the Type tab, or photograph your paper signature and add it with Add Photo.
• Xournal++ saved a .xopp file. That is the project format; export to PDF to get a document you can send.
• The browser blocks the download. Allow downloads for sigpdf.com in the browser’s site settings and click the button again.

Signing on other systems: Windows, Mac or Android.