How to add a watermark to a PDF for free, without uploading it

How to add a watermark to a PDF

Adding a watermark to a PDF in AtlasDocs takes one field and one click: you type the text, such as CONFIDENTIAL or DRAFT, and the tool stamps that word across every page, diagonally, in semitransparent gray, on top of the content. The downloaded file is a copy with the mark; the original stays untouched. Everything happens in your browser, with the document never sent to any server.

1. Open the Watermark tool and upload your PDF. You can upload several at once.
2. Type the text in the box under the "Watermark" heading (it shows "E.g.: CONFIDENTIAL" inside). Short text, about the length of CONFIDENTIAL, works best; the button only unlocks once you've typed something.
3. Click "Apply and download" (with several files, the button reads "Apply to 3 PDFs"). Each PDF is downloaded with the suffix -marca-dagua in its name.

The mark always comes out the same way: gray, semitransparent, diagonal and centered on every page. There are no settings for color, position, size or opacity: the only thing you choose is the text. Want a different word? Just generate it again from the original, which is never altered.

How the watermark looks: can you change its color, position or size?

• Gray text at 30% opacity: the content underneath stays readable, and the mark stays visible on screen and in print.
• Tilted 45 degrees, running through the center of the page. Fixed position, no corner to choose.
• Size proportional to the page: the font size is one-eighth of the page's shorter side, so on a Letter or A4 sheet the capital letters come out about three-quarters of an inch (1.9 cm) tall. No size control.
• Bold, in a standard font (Helvetica), on every page of the document, cover included.
• Drawn on top of the content, not behind it: over a dark image it may be less visible.

What a watermark is for

A watermark is that semitransparent text running across the page on top of the content, without keeping you from reading what's underneath. It doesn't lock the document: it identifies where it came from and what state it's in, and discourages anyone from passing a copy off as the final or public version. If the document needs a real lock, see how to password-protect a PDF: without the password, the file won't even open.

• Protecting authorship, putting the company name or author on every page of a proposal or handout.
• Marking the document version, with "DRAFT," "COPY" or "NOT FINAL," so nobody signs the wrong one.
• Marking confidential documents as "CONFIDENTIAL" before sharing them internally.
• Signaling restricted use, like "SAMPLE" or "INTERNAL USE," to discourage redistribution.

Does a watermark protect a PDF? Limits and common mistakes

• The mark doesn't prevent copying and isn't tamper-proof: whoever has the file can still copy the text and images, and a PDF editor can delete it. It identifies and discourages; it doesn't block.
• Long text runs off the page: the letters don't shrink to fit and there's no line wrapping. On a Letter or A4 sheet, CONFIDENTIAL or DO NOT COPY fits entirely; CONFIDENTIAL PROPOSAL, or a long company name, is already too long and gets cut off at the ends. Stick to one word or two very short ones.
• The tool can't take the mark off later: it's written into the page itself, not onto a layer you can switch off. Always keep the unmarked original.
• Text only: the tool doesn't accept a logo or an image as a watermark.
• A password-protected PDF doesn't get the mark, not even one that opens normally but blocks printing or copying: you'll see "Could not apply the watermark." Remove the password first with the Remove PDF password tool (you need to know the password). If you want both a mark and a password, add the mark first and then protect the file with the Protect PDF with password tool.
• Emojis and symbols like arrows or ✓ aren't accepted, and neither are letters and characters from other writing systems, such as Greek, Russian or Chinese: you'll see "Could not apply the watermark." Accented letters, ç, ñ, € and quotation marks work fine.
• Download and check a page full of content: since the mark sits on top, make sure it doesn't get in the way of a table or a signature.

The mark doesn't hide anything underneath either: ID numbers, amounts and signatures stay readable. If the PDF has data that must not circulate, see how to redact sensitive data in a PDF before sending it.

How to watermark several PDFs at once

Upload all the files together and type the text only once: the tool applies the same mark to each PDF, one after the other, and downloads one file per document, each with the suffix -marca-dagua. It's the quick way to mark a batch of proposals or handouts with "CONFIDENTIAL" or the company name, without repeating the job file by file. If one of the PDFs fails (a password-protected file, for example), the batch stops there: the ones above it in the list have already downloaded, and the ones after it stay unmarked. Remove that file and the ones already done from the list, then click again.

How to check the result

Open the downloaded PDF and go to a full page: the mark should run through the center in light gray, readable but not hiding the text. If the document mixes portrait and landscape pages, the mark adapts to each one, because the size is worked out page by page from the shorter side of each sheet. The exception is pages that were rotated after the file was made, for example with the Rotate tool: on those, the mark may run along the other diagonal or come out upside down, so check them one by one. Keep the original somewhere else: the mark has no undo button.

Everything is done inside your browser: your PDF is never uploaded to any server, which matters a lot when the document you're marking is confidential.

Several PDFs uploaded together get the same text. If each file needs a different mark, upload them one at a time.