everyday mac tools

Add a watermark, header or footer to a PDF on a Mac

· 6 min read

Preview has no watermark command. The free route on a Mac is Automator, whose Watermark PDF Documents action places an image on every page and can be saved as a Finder right-click action so you never open Automator again.

Headers, footers and page numbers are a different question. macOS has no built-in way to add them to a PDF that already exists, so the usual answer is to put them into the source document before you export.

What macOS gives you, and what it does not

Preview can put a text box or a pasted image on a page using the Markup toolbar (View, Show Markup Toolbar). That is an annotation: it sits on top of the page, anyone can click it and press Delete, and you do it one page at a time. Fine for a single-page handout marked DRAFT, not for a fifty-page report.

Automator, in your Applications folder, has a PDFs library with a Watermark PDF Documents action. It takes an image, applies it to every page, and gives you scale, opacity, position and a choice of whether the mark sits above or below the page content. It works on a folder full of files.

The print dialog adds headers and footers in some apps but not to PDFs. Safari has a print option for them, so a web page printed to PDF gets a title and a date. That does nothing for a PDF you already have.

What is genuinely missing from macOS is a way to stamp text along the top or bottom of an existing PDF: page numbers, a case reference, a confidential line, a production number.

Make the watermark artwork

The Automator action wants an image, so make one first. Two things matter: the words, and a transparent background.

  1. Open TextEdit, make a new document, and type the text: CONFIDENTIAL, DRAFT, a recipient’s name, a matter number.
  2. Select it and set a large font in a mid gray (Format, Font, Show Colors). Gray stays readable over text; black does not.
  3. File, Export as PDF.
  4. Open that PDF in Preview and choose File, Export, with Format set to PNG and Resolution at 300 pixels per inch.
  5. Still in Preview, show the Markup toolbar and use Instant Alpha to select the white background, then press Delete. Export again as PNG with the Alpha box checked, which gives you a mark with nothing behind it.

For a diagonal watermark, build it in Pages or Keynote instead, where a text box can be rotated to any angle in the Format panel under Arrange. Preview only rotates in ninety-degree steps. Keep the PNG somewhere permanent, because you will point at it every time.

Stamp every page with Automator

  1. Open Automator and choose Workflow.
  2. From the Library, drag Copy Finder Items into the workflow first and set a destination folder. This is the step people skip and regret: it means the watermark is applied to copies and your originals stay as they are.
  3. Drag Watermark PDF Documents in below it, from the PDFs group.
  4. Click Add in that action and choose your PNG.
  5. Set Scale and Opacity. Start around twenty percent and adjust after looking at a real page. Set the position, and choose whether the mark goes above or below the page content.
  6. Drag the PDFs onto the workflow area, or add a Get Specified Finder Items action at the top and choose them there.
  7. Click Run, then open the result and check which folder the files landed in.

Do that on a single test file before you point it at a set. Opacity and scale always need one adjustment, and it is faster to find that out on one page than on two hundred.

Turn it into a right-click Quick Action

Once the settings are right, make it something you can use from Finder.

  1. In Automator, File, New, and choose Quick Action.
  2. At the top, set “Workflow receives current” to PDF files, in Finder.
  3. Rebuild the same two actions: Copy Finder Items to an output folder, then Watermark PDF Documents with your image and settings.
  4. Save it with a name you will recognize, such as “Watermark confidential”.

It now appears when you right-click a PDF in Finder, under Quick Actions, and you can show, hide or assign a keyboard shortcut to it in System Settings, Keyboard, Keyboard Shortcuts, Services. Make one per watermark you use regularly rather than one you keep editing.

Headers, footers and page numbers

There is no honest macOS route for adding these to an existing PDF. The options are:

Put them in the source and export again. In Pages, the Document panel has header and footer fields per section, and Insert, Page Number puts a live number in one. Most document apps have the equivalent. This is the right answer whenever you still have the original.

Print to PDF from an app that prints them. Useful for web pages and email, not for documents that are already PDFs.

Use a PDF tool that stamps them. For legal and records work this is usually Bates numbering rather than a plain footer: a unique sequential number on every page of a production, which is what people refer to in correspondence afterwards. Bates numbering on a Mac covers why the numbering has to be stable.

Basalt has both in one window: a Watermark tool that also does headers and footers, and Bates Numbers as a separate tool, alongside merge, split, compress, OCR, forms, signing and redaction. Every tool writes a new file rather than modifying the original, and its Procedures feature records a set of steps so the next batch gets the same watermark and numbering. It does not edit PDF text like a word processor.

A watermark is a label, not a lock

Watermarks get asked to do work they cannot. One added as an annotation can be selected and deleted in seconds. One drawn into the page content is harder to remove, but the page can still be cropped, re-rendered, screenshotted or covered. Nothing you stamp on a page prevents the text underneath from being selected and copied.

PDF permissions are similar. A file can carry a permissions password saying printing or copying is not allowed, and viewers are free to ignore it; plenty do. The only password that actually withholds content is the one required to open the file.

So watermark for the reasons it works: marking a draft as a draft, showing which copy went to whom, reminding a reader of a confidentiality obligation. If the content itself must not be readable, remove the content. Why a black box on a PDF does not redact anything covers the version of this mistake that does real damage, and redacting records for a public records request covers the process when the removal has to hold up.

Questions

Can I watermark in Preview without Automator? For one page, yes. Show the Markup toolbar, add a text box or paste an image, and position it. It is an annotation, so it is removable and it applies to that page only.

Should the watermark go above or below the page content? Below looks better on text pages, because the words stay crisp and the mark shows through the white. Above is the only option that works on a scan, since a scanned page is an opaque image and anything behind it is invisible. Lower the opacity when you put a mark on top.

How do I remove a watermark from a PDF someone sent me? If it was added as an annotation, open Tools, Show Inspector in Preview, find it in the annotations list and delete it. If it was drawn into the page content there is no clean removal. Consider whether removing it is yours to do.

Does a watermark stop people printing or copying the document? No. It marks the page, and that is the whole of its effect. Anything stronger has to come from not sending the content at all.