How-To

How to Watermark a PDF for Free: Add Text or Image Watermarks

Sep 15, 2026 · 6 min read

Quick summary: To watermark a PDF for free, open it in Preview on Mac, add a text box or image with low opacity in the Markup toolbar, and save. For a true background watermark across all pages, use LibreOffice Impress (free, cross-platform) or Ghostscript. Online tools can apply a batch text watermark in seconds without any install.

A watermark marks a document as “Draft”, “Confidential”, “Sample”, or branded with your logo — visible on every page so recipients know its status. You do not need Adobe Acrobat for this. The methods below are free and work on any platform. After watermarking, upload the PDF to our free AI PDF reader to verify the content reads correctly.

How to watermark a PDF on Mac

Method 1: Preview — quick text watermark

Preview can add a text overlay to any page:

Open the PDF in Preview.
Click View → Show Markup Toolbar.
Click the Text tool (T) and draw a text box in the center of the page.
Type your watermark text (e.g. “CONFIDENTIAL” or “DRAFT”).
Select the text, increase the font size (48–72pt works well for a full-page watermark).
Click the color picker in the Markup toolbar to set the text color to light gray or a low-opacity color.
Rotate the text box: hold Cmd while dragging the rotate handle to tilt it 45°.
Repeat for each page (or use the sidebar to select all page thumbnails if your tool supports multi-page).
Save with Cmd + S.

Limitation: Preview applies the watermark as an annotation, not as a background layer. The text may appear above the page content rather than behind it.

Method 2: Preview — image watermark

To use your logo or a “DRAFT” stamp image as a watermark:

Prepare a PNG with a transparent background and the desired opacity (use Preview or another image editor to reduce opacity to 20–30%).
Open the PDF in Preview.
Go to Edit → Insert → Page from File — wait, this adds a page. Instead, use drag-and-drop: open the image separately in Preview, then drag it from the Preview window onto the PDF page.
Resize and position the image.
Save.

How to watermark a PDF with LibreOffice (free, all platforms)

LibreOffice Draw is the best free desktop option for a true background watermark across all pages:

Open LibreOffice Draw (not Writer).
Go to File → Open and select your PDF.
To add a watermark that appears on every page, go to Insert → Header and Footer — or use the Master Slide approach:
- Go to View → Master (in LibreOffice Impress) or View → Page (in Draw).
- Add your text (e.g. “CONFIDENTIAL”) in a large, rotated, low-opacity text box.
- Apply it as the background layer.
Export: File → Export as PDF with form fields enabled.

Simpler Draw method (per page):

Open the PDF in LibreOffice Draw.
On the first page, draw a text object with your watermark text.
Set opacity: right-click the object → Character → Font Effects → Font Color (with opacity).
Copy the text object, switch to each page, and paste.
File → Export as PDF.

How to watermark a PDF with Ghostscript (command line)

Ghostscript can stamp a text watermark across every page with one command. First, create a watermark PostScript file:

watermark.ps:

/Helvetica-Bold findfont 60 scalefont setfont
gsave
0.15 setgray
200 400 translate
45 rotate
(CONFIDENTIAL) show
grestore

Then apply it to every page:

gs -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -dSAFER \
   -sOutputFile=watermarked.pdf \
   watermark.ps input.pdf

The watermark text is drawn on every page before the page content renders. Adjust the coordinates (200 400) and rotation (45) to position it. 0.15 setgray sets a light gray; 0.5 setgray is medium gray.

How to watermark a PDF online (free, no install)

Several free browser-based tools apply text or image watermarks without sign-up. Search for “watermark PDF free online”:

Upload your PDF.
Type the watermark text or upload a watermark image.
Set position (center, diagonal), opacity, font size, and color.
Download the watermarked file.

Privacy note: Online tools upload your file to a remote server. Avoid them for confidential or sensitive documents.

Watermark position and style guide

Use case	Text	Size	Opacity	Angle
Legal draft	DRAFT	72pt	20–30%	45° diagonal
Confidential	CONFIDENTIAL	60pt	25%	45° diagonal
Sample / preview	SAMPLE	72pt	20%	45° diagonal
Branded	Your company name	48pt	15%	0° or 45°
Page number watermark	© 2026 Company	10pt	60%	0° (footer)

A diagonal 45° watermark at 20–25% opacity is the industry standard — visible enough to be noticed but light enough that the underlying text remains readable.

How to remove a watermark from a PDF

Removing a watermark you added is straightforward:

Preview annotation watermark: click the text box or image, press Delete, save.
Flattened watermark: if the watermark was baked into the page content (via Ghostscript or a PDF export), it cannot be removed without rasterizing and re-editing the pages.

For a watermark added by someone else as a flattened layer, professional tools (Acrobat Pro) can sometimes remove it, but free tools generally cannot.

Frequently Asked Questions (FAQ)

Can I add a watermark to only some pages of a PDF?

Yes. Extract the pages you want to watermark (see how to extract pages from a PDF for free), apply the watermark, then merge the watermarked pages back with the unwatermarked pages using a PDF merge tool.

How do I watermark a PDF without it being removable?

Flatten the PDF after adding the watermark — this bakes the watermark into the page content so it cannot be deleted as an annotation. See how to flatten a PDF for free. Even flattened watermarks can theoretically be removed by advanced image editing, but it requires significant effort.

Can I add an image logo as a watermark instead of text?

Yes. Prepare your logo as a transparent PNG, reduce its opacity in an image editor (Preview, GIMP, or Photoshop) to 20–30%, then insert it as an image annotation in Preview or LibreOffice Draw. Position it in the center or corner of each page.

Does watermarking change the original text of the PDF?

No. A watermark added as an annotation sits on top of the existing content. The underlying text, images, and structure remain unchanged. If you flatten the PDF afterward, the layers merge — but the original content is still intact underneath the watermark.

Why does my watermark only appear on one page?

In Preview, you added the text box to a single page. To apply it to all pages, you need to copy and paste the annotation onto each page individually, or use a tool that supports document-level backgrounds (LibreOffice Master view or Ghostscript).

How to flatten a PDF for free — lock the watermark permanently before sharing
How to password protect a PDF for free — add extra protection alongside the watermark
How to add page numbers to a PDF for free — add page numbers at the same time as the watermark
How to redact a PDF for free — permanently hide sensitive content before distributing