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How to add a watermark to a PDF (text or logo)

Adding a watermark to a PDF isn't just decoration. It's the fastest way to make something clear without opening the document and explaining it:

• A contract or quote you're sending before the final version, so no one mistakes it for the real thing (DRAFT).
• An internal report that shouldn't leave the company (CONFIDENTIAL).
• Invoices or dossiers with your logo, so it's clear where they came from even if someone forwards them without context.
• A copy you hand to a client or supplier, different from the original you keep (COPY).

In every case the problem is the same: you need to overlay something (text or an image) on the pages of an existing PDF, without rebuilding the document from scratch.

Text or image: pick one

Watermark PDF supports two modes, and you have to pick one: text or image, never both at once.

• Text: any word or short phrase (max 200 characters): "DRAFT", "CONFIDENTIAL", your company name, a date... You can send the raw PDF with the text as a URL parameter, or send everything together as JSON.
• Image: your logo in PNG or JPEG, base64-encoded. Here only JSON works, because a PDF and an image can't both travel as raw binary in the same request.

Where it goes and how it looks

By default the watermark comes out centered, light gray (#808080), rotated 45 degrees: the classic diagonal stamp, visible without getting in the way of the text underneath. All of that can be changed:

• position: center or one of the four corners (top-left, top-right, bottom-left, bottom-right).
• opacity: from 0.05 (nearly invisible) to 1 (solid); defaults to 0.3.
• rotation: any angle in degrees you want. Unlike rotating the whole page, this only rotates the text or image, so there's no restriction to multiples of 90.
• With text: font_size (8–200, default 48) and color in hex (default #808080).
• With an image: scale (0.05–1, default 0.3), the fraction of the page width the logo will take up.

Only on some pages

By default the watermark applies to every page in the PDF. To mark just a range (say, the appendices but not the cover page) use pages with a list like 1-3,5, numbered from page 1.

FAQ

Can I use my logo instead of text? Yes. Send the image (PNG or JPEG) base64-encoded inside a JSON body, in the image field. It's the one case where JSON is required: with text you can send the raw PDF instead if you prefer.

How much does it cost to watermark a 100-page PDF? Same as a 1-page one: 1 watermark = 1 credit, whether it's applied to one page or all of them.

Can the watermark be removed afterward? Not with this tool. The watermark is drawn onto the page content, just like any other text or image in the PDF. If you need a clean version later, generate it from the original, unmarked document, not from this result.

Is the output a straight PDF or JSON? It can be forced with output=pdf or output=json. By default, sending the raw PDF returns a PDF, and sending JSON returns JSON with the PDF as base64.

Try these tools

You'll find the full instructions for Watermark PDF, with examples for n8n, Make and your own code. And if you don't have an account yet, you can create one for free.