How to add a watermark to a PDF: a step-by-step guide

Drop the PDF anywhere on the page, or press Add files - one file or several. The thumbnails show a watermark at once: "CONFIDENTIAL" across the middle, until you change it. A Word, Excel or PowerPoint file or a photo works too - it is turned into a PDF as it arrives.

Under Watermark, Text takes any words you type. Image takes a PNG or JPG of up to 8 MB - a transparent PNG works best, since it lays only the logo on the page, not a white box around it.

With Pro, Save to my account under the picture keeps your logo, so it is one click away next time. Only the picture is kept - never the document.

• Font (Helvetica, Times or Courier), Bold, Italic and Color - for a text watermark.
• Size - as a share of the page width, so the same setting suits an A4, an A3 and a landscape page alike.
• Opacity - how strongly it shows; 20-30% marks a page without making it hard to read.
• Blend into the page - dark text shows through the watermark, as if it sat behind the content.

Under Placement, Position puts one watermark at any of nine spots - the middle, a corner, an edge - with a Margin from the edge, and Angle turns it anywhere from -90° to 90° (0°, 45°, -45° and 90° are one click away).

Repeat covers the whole page with a grid of copies instead, Sparse, Medium or Dense - harder to crop off a screenshot or a photo of the page.

Every page is stamped by default. The bar above the thumbnails picks fewer - Odd, Even, Landscape, Portrait, Every Nth, a range typed into the field ("2-5") - or click a thumbnail to add or remove that page.

The magnifier in a thumbnail's corner opens the page large, with the watermark drawn as it will be saved.

Above the file list, Apply to decides whose settings the rail shows:

• Selected file - the settings belong to the file selected in the list, so each file can get its own watermark - a client's name on each copy, say. A file with its own settings wears an own badge.
• All files - one watermark for every file. The files' own settings are set aside, not lost.

Copy to the other files under the options gives the settings you see to every other file as its own. More than one result is saved as a ZIP.

Press Add watermark. The line under the button counts the stamped pages. The file is saved to your device at once; the button then says Saved and turns into Save, which saves the same file again. Bookmarks, links and form fields survive.

A watermark marks a document; it doesn't lock it - someone with an editor can take it off. To stop opening or copying, Protect PDF with a password.

Without an account, and with a free one, you can stamp two files in a run, each up to 15 MB. With Pro there is no limit on the number or the size, and you can save a whole look - text, size, opacity, place - as a preset.

• Page numbers as well? Page Numbers.
• A signature on the last page? Sign PDF.
• Text or a stamp on one page only? Edit PDF.