How to Sign a PDF on Linux for Free (Ubuntu, Fedora, Mint)

The quickest way to sign a PDF on Linux is in your browser: open Docsigns in Firefox or Chromium, upload the PDF, draw, type or upload your signature, drag it into place and download the signed PDF. It works the same on Ubuntu, Fedora, Mint, Debian or Arch, with nothing to install and no account.

Linux has good desktop options too, and if you sign documents every day, one of them may suit you better. This guide covers the browser method step by step, then the main desktop alternatives, and finishes with the difference between the electronic signature most people need and the certificate-based digital signature some organisations ask for.

Sign a PDF on Linux in the browser (any distro)

Because the signer runs in the browser, it doesn't matter which distribution, desktop environment or package manager you use. Any current version of Firefox, Chromium, Chrome, Brave or Vivaldi will do.

1. Open the signer. Go to docsigns.online. The upload area is on the home page.
2. Upload your document. Drag the PDF from your file manager (Nautilus, Dolphin, Thunar, Nemo) onto the page, or click to browse.
3. Create your signature. Draw it with a mouse, touchpad or touchscreen; type your name and choose one of six cursive fonts; or upload an image of your handwritten signature.
4. Pick a pen colour. Black and blue are the usual choices for documents; red, green, orange and purple are also available.
5. Place it. Drag the signature onto the signature line, resize it to fit, and move to other pages if the document needs more than one signature or initials.
6. Add a date if needed. Place a date next to the signature and pick the format the document expects.
7. Download the signed PDF. It saves to your Downloads folder, with no watermark.

The how it works page shows the same three stages (upload, sign, download) if you'd like a visual walkthrough first.

What happens to your file

For many Linux users, privacy comes down to one question: does my document get uploaded somewhere? The honest answer depends on the file type:

• PDF files are signed in your browser. The PDF itself is not uploaded to a server.
• DOC and DOCX files are first converted to PDF on a server, then signed. If you'd rather keep a Word document local, export it to PDF yourself first (LibreOffice Writer: File → Export as PDF) and sign the PDF.

The privacy policy has the full details.

Desktop alternatives on Linux

If you prefer native applications, these are the common free options. Each can place a signature image on a PDF; how smooth it is varies.

Option	How you add the signature	Good for	Trade-offs
Browser signer (Docsigns)	Draw, type or upload, then drag into place	Any distro, occasional signing, Word files too	Needs an internet connection to load the page
Xournal++	Open the PDF, insert an image of your signature or write with a pen tablet, export as PDF	People with a drawing tablet, annotating PDFs	Needs a separate signature image or a tablet; exporting is an extra step
LibreOffice Draw	Open the PDF, insert your signature image, export as PDF	Already installed on many distros	PDF import can shift fonts and layout on complex documents
Okular (KDE)	Annotation tools, plus certificate-based digital signing	KDE users; organisations that issue certificates	Certificate signing needs a certificate set up first

A note on LibreOffice Draw

Draw is often suggested because it's already there, and for simple one-page forms it works. The catch is that Draw converts the PDF into editable drawing objects, so on documents with unusual fonts, tables or tight layouts you may see text reflow or move. Always compare the exported file against the original before sending it. For a contract or lease where the layout matters, a tool that places the signature on top of the untouched PDF is safer.

Making a signature image for desktop tools

Desktop tools usually need your signature as an image. Sign a plain white sheet with a dark pen, photograph it in good light, crop tightly and, ideally, make the background transparent so it doesn't cover lines on the page. You can reuse that same image in the browser signer with the upload option, which keeps your signature consistent across documents.

Electronic signature or digital signature?

This is where Linux guides often mix things up. There are two different things people call "signing a PDF":

• An electronic signature is your signature mark (drawn, typed or an image) placed on the document. This is what Docsigns produces, and it's what most landlords, employers, schools and small businesses mean when they ask you to "sign and send back".
• A certificate-based digital signature uses a certificate, often issued by a government ID scheme or a trust service provider, to cryptographically seal the file. Some public administrations, courts and companies require this specifically. On Linux, tools such as Okular, LibreOffice or national signing apps handle it once a certificate is installed.

Docsigns does not create certificate-based or qualified digital signatures. If the sender asks for one, or mentions a specific certificate, smart card or national ID app, use the tool they name instead.

For most everyday agreements, electronic signatures are accepted under laws such as ESIGN and UETA in the US and eIDAS in the EU. Some documents, including property transfers, wills and certain financial instruments, may require more, such as a qualified signature or a witness. This is general information, not legal advice; if the stakes are high, check with the other party or a lawyer.

Signing a Word document on Linux

People often receive a DOCX rather than a PDF, and opening it in LibreOffice Writer can shift the layout slightly if the sender used fonts you don't have installed. You have two sensible routes:

1. Upload the DOCX directly to the signer. It is converted to PDF on a server, then you sign it in the browser as usual and download a signed PDF.
2. Export to PDF locally first. Open the file in LibreOffice Writer, check that the pages look right, choose File → Export as PDF, and sign that PDF. This keeps the file on your machine and lets you spot layout problems before you sign.

Either way, you send back a PDF, which is what most senders expect from a signed document: it looks the same on every device and is harder to change by accident than an editable Word file.

Troubleshooting on Linux

• The drawn signature looks shaky. Touchpads are hard to sign with. Try the typed option with a cursive font, or upload an image of a signature written on paper.
• The download doesn't appear. Check your browser's download settings; some Flatpak or Snap browsers ask where to save, or save into a sandboxed folder. Look in ~/Downloads first.
• The file picker can't see a folder. Sandboxed Flatpak and Snap browsers only see certain directories by default. Drag the file from your file manager instead, or move it into ~/Downloads.
• The signed PDF opens differently in another viewer. Open it in two viewers (for example Firefox's built-in viewer and Evince or Okular) to confirm the signature sits where you placed it before sending.

After signing

Open the signed PDF once and check every page: signature on the right line, date in the right place, initials where they were requested. Rename the file so it's easy to find later (for example lease-signed-2026-09.pdf), keep a copy, and reply to the sender with it attached. If you sign documents regularly, the other guides on the Docsigns blog cover specific documents such as leases, NDAs and offer letters.