Add a watermark to a PDF

What Add Watermark does, and when you need it

Add Watermark stamps words or a picture across the pages of a PDF and saves the PDF with it. Type CONFIDENTIAL, DRAFT, COPY or your own words, or choose a logo, then pick its size, colour, opacity and angle, and whether it appears once in the middle of each page or repeated across it. Every page's card shows the watermark in place before you save. It all happens inside your browser, with nothing uploaded, no sign-up, and no watermark of ours added to yours.

A watermark tells everyone who sees a page what it is, or whose it is. People use it to:

• Mark a draft, so nobody mistakes a version under review for the final one.
• Mark private papers as confidential, such as salary details, board papers or a report shared before it is public.
• Mark copies of ID cards and certificates with what they are for, like "For bank account opening only", so a copy can't easily be passed off for something else.
• Brand documents with a company or school logo: price lists, brochures, study notes and question papers.
• Mark samples and previews, like a design or a chapter shared before it is paid for, with SAMPLE or PREVIEW.
• Mark paid bills, with PAID across an invoice or a receipt.

What a watermark can and can't do

A watermark is a label, not a lock. It is worth being clear about this before relying on one.

• It can make a page's status or owner obvious to anyone who sees it, on screen, on paper and in a screenshot. It discourages casual copying, because a copied page carries the mark with it.
• It can't stop anyone opening, reading, printing or copying the PDF. The words underneath stay readable, which is the point.
• It can be removed. The watermark is drawn on top of each page as text or a picture. Anyone with PDF editing software can select it and delete it, and some tools are made to do exactly that. A repeated watermark is more work to remove than one in the middle, but it can still be done.
• It isn't hidden tracking. It is a visible mark, not a secret code that identifies who leaked a copy.

To keep a PDF from being opened by the wrong people, protect it with a password before you send it, and send the password another way, like a phone call or a separate message. A watermark and a password do different jobs, and work well together.

Step by step: adding a watermark on this page

1. Add your PDF. Press Choose PDF files and pick one or several, drop PDFs anywhere on this page, or paste one you copied. To try it first, press Try with a sample PDF: it makes a 3-page rental agreement.
2. Choose words or a picture. Under Watermark, Text is chosen at first, with CONFIDENTIAL typed in. Type your own words or press one of the ready-made ones. For a logo, choose Picture or logo, then Choose a picture.
3. Set how it looks. Move the Size and Opacity sliders, pick a colour for words, and choose Diagonal or Straight.
4. Choose Once or Repeated, and All pages or Only some, where you type pages like 1-3, 5.
5. Check the cards. Each page's card shows the watermark exactly where it will go, and says With watermark or No watermark under it.
6. Save and download. Press Add watermark. A row appears under the tool with the new file's name, like report-watermarked.pdf, the pages stamped, the size before and after, the time taken and "nothing uploaded". Press Download.

If you change an option after saving, the result goes away and the button comes back, so the file you download always matches the cards.

Words for a watermark

Short words in capitals read best across a page. The ready-made ones cover the usual needs:

• CONFIDENTIAL: private papers meant only for the people they are sent to.
• DRAFT: a version still being worked on.
• COPY: a copy, not the original, such as a copy of a certificate.
• SAMPLE: a preview or an example.
• PAID: an invoice or a bill that has been settled.
• DO NOT COPY: a request not to copy or share the pages.

You can type anything up to 200 characters, like a company name, a date or "For visa application only". Watermark words are drawn in Helvetica Bold, a standard font every PDF reader has, so the file needs no font of its own. That font has Latin letters, with accents such as é and ü, digits and common punctuation, but not other scripts like Devanagari, Tamil or Arabic. If you type a character it can't draw, the box says which, and nothing is saved until it is changed.

Size, colour, opacity and angle

Opacity sets how much of the page shows through the watermark. At a low opacity, the words under it stay easy to read, and a printed page stays usable. A solid watermark covers what is beneath it, so keep it at 100% only for a small mark in a corner of the page, like a logo on a plain area.

A point is the unit for the size of type: 72 points make an inch, about 2.5 cm. For comparison, body text in most documents is 10 to 12 points. At 60 points, CONFIDENTIAL is about 16 cm wide, and at 150 points, a short word like COPY is about 15 cm wide, most of the 21 cm width of an A4 page.

Once in the middle, or repeated across the page

Once puts the watermark in the middle of each page, as a reader sees it. It is the usual choice for DRAFT, CONFIDENTIAL and PAID: clear, and easy to read past.

Repeated fills the page with rows of the watermark, with a gap between copies and every other row shifted along by half a step, like bricks in a wall. A smaller size works best: try 30 to 48 points for words. Repeated marks are harder to cut off a page or cover up, so they suit ID copies and previews you share with people you don't know. On the sample's A4 pages, red 36-point CONFIDENTIAL repeated diagonally makes 27 copies on each page, some running off its edges, and the cards show the same 27.

Each page is measured on its own, so the watermark sits in the middle of every page, and a repeated one covers every page from edge to edge, whatever their sizes. Pages that are turned or landscape get the watermark the right way up for the reader too.

A logo or picture as a watermark

Choose Picture or logo, then Choose a picture, and pick a PNG, JPG, WebP or GIF picture from your device, or drop one on the page. The cards show it at once.

• PNG with a see-through background works best for a logo: only the logo shows, not a white box around it. See-through parts are kept in the PDF.
• Size is a share of each page's width: at 40%, the size it starts at, the picture is 40% as wide as the page, and its height follows its own shape.
• Opacity, angle and Repeated work as they do for words. A logo at 20% to 30% opacity in the middle of the page is a common look for letterheads and brochures.
• Big pictures are made smaller first, to at most 1000 pixels on their longer side. That is sharp enough for a logo 8 cm wide on paper, and keeps the file small: the picture is stored once and used on every page.

In our tests, a 14-page paper with a 600 by 200 pixel logo on every page came out 6 KB bigger than with a word watermark, because the logo is stored once. A photo adds more than a logo, because photos don't pack down as small.

Marking copies of ID cards and certificates

Copies of Aadhaar and PAN cards, passports, marksheets and bank statements are asked for everywhere: bank accounts, SIM cards, rentals, jobs and admissions. Writing the purpose across the copy, with the date, makes it harder to reuse for something else. A watermark does this neatly on a PDF:

1. Type the purpose and the date in the Text box, like For bank account opening only, 7 Oct 2026.
2. Choose Repeated, with a size of about 24 points, so the words cross the whole card.
3. Keep the opacity at 30% to 40%, so the details on the card stay readable to the person checking it.
4. Save, and send the marked copy, not the original scan.

This is a sensible habit, not a guarantee: as above, a determined person with editing software can remove a watermark. Share ID copies only with people and services you trust, and only when they need them.

What stays the same in your PDF

The watermark is drawn on top of each page. Nothing already on the page is redrawn, moved or compressed again, and every page stays in its place:

• Text stays text, so it can still be searched, selected and copied.
• Pictures and scans keep every pixel.
• Links still work, and bookmarks still lead to the right pages.
• Forms keep their fields and anything already filled in. Form fields are shown above the page, so a watermark sits under the boxes, not over them.
• Screen readers skip the watermark, which is marked as page decoration, not part of the text to read aloud.
• The size barely changes for words: the watermark is written once and shared by every page of the same size, and no font is added.

A PDF locked with a password to open can't be used until it is unlocked. One that only restricts editing is stamped anyway, and the new PDF opens without those restrictions; the result says so. A digitally signed PDF can be stamped, but the changed copy no longer carries a valid signature, and the result says that too.

Real results from our tests

We stamped these PDFs in Chromium 141, the open-source browser Google Chrome is built on, on a Linux computer with 4 processor cores and 16 GB of memory. Times are what the page reported, from pressing the button to the finished file. Your device may be faster or slower.

• 0.1 sto stamp the 3-page sample agreement
• 0.6 sto stamp all 117 pages of a textbook with repeated words
• 5.7 sto stamp a logo on every page of a 400-page, 455 MB scan
• 0 bytessent to any server

We drew every page of each result with pdfium, the PDF engine inside Chrome, and compared it with the original page: the only change on each stamped page was the watermark, where the card had shown it, and pages left unstamped were unchanged. Every letter of the original text was still there. The textbook kept all 35 of its bookmarks and 509 links, and the form kept all 8 filled-in answers.

Times are the middle of three or more runs, except for the 400-page scan, stamped once. Stamping the textbook took the browser about 56 MB more memory than when idle, the 42-page scan about 280 MB and the 400-page scan about 1.9 GB, because the file and the new PDF are both held in memory while it is made. Words set at a slant, like a diagonal watermark, are in the file as text, and pdfium reads them whole; some other text tools read them in pieces.

Stamping several PDFs at once

Add as many PDFs as you like, all at once or a few at a time with Add more PDFs. Each file gets its own heading with a coloured dot, and its pages follow it. The same watermark goes on every file. To take a file out, press the X on its heading.

The button says how many PDFs will be saved, as in Add watermark to 3 PDFs. One PDF downloads on its own; several come in one ZIP file, watermarked-pdfs.zip, with a PDF for each, named after its original, like quote-watermarked.pdf. With Only some, the typed pages count from the first page of each file, and a file that has none of them is left out.

This suits a set of papers going to one place, like the copies for a rental or a loan: mark them all with the same purpose in one go. To join them into one PDF first, use Merge PDF.

Private: your files stay on your device

The papers people watermark are private almost by definition: confidential reports, ID copies, contracts, drafts not yet shared. With NoUploadPDF they never leave your phone or computer, and neither does your logo. Your browser opens the PDF, and pdf.js draws the small pictures of its pages. Then our pages engine, written in Rust and compiled to WebAssembly, adds the watermark in a background worker on your device, so the page stays responsive while it works.

The page can't send your files to another site, even by mistake. Its Content Security Policy, a rule the website gives your browser, tells the browser to block the page from sending data to any other site. There is no account to create and nothing to sign in to. If you like, you can check in your browser's network panel that nothing is uploaded.

Compared with tools that upload your files

Many online PDF tools upload your files to their servers, add the watermark there and send the result back. Here is how that compares with working on your own device:

Many upload-based tools are well made, and some promise to delete your files after a while. A file that is never uploaded needs no such promise.

Use it on Android, iPhone, Windows and Mac

There is nothing to install: Add Watermark runs in an up-to-date browser on phones, tablets and computers.

• Android

  Open this page in Chrome or another up-to-date browser and tap Choose PDF files. Set the watermark, scroll down to check the cards, then tap Add watermark. A logo can come from your gallery or files. The new PDF is saved to your Downloads folder.

• iPhone and iPad

  Use Safari. Tap Choose PDF files and pick a PDF from the Files app. A logo can come from Photos or Files. The new PDF usually goes to Downloads in the Files app.

• Windows, Mac, Linux, Chromebook

  Click Choose PDF files, or drag PDFs onto the page. Drop a PNG or JPG on the page to use it as the watermark. The new PDF goes to your Downloads folder.

On a phone, the options come first and the cards follow, two to a row. The sliders work with a finger, and the button stays in view at the bottom of the screen.

Problems and quick fixes

• The button can't be pressed. The text box may be empty or hold a character the font can't draw (it says which), Picture or logo may have no picture yet, or Only some may need pages typed, like 1-3.
• The watermark hides the text under it. Lower the opacity to 20% or 30%, or pick grey.
• The watermark runs off the page. Lower the size until the cards show it inside the page, or choose Straight: a long line of words at an angle needs more room.
• A logo has a white box around it. The picture has a white background. Use a PNG with a see-through background, often called a transparent PNG.
• A picture can't be opened. Some formats, like HEIC photos from iPhones, don't open in every browser. Save it as PNG or JPG first.
• Form fields show over the watermark. That is how PDF readers draw forms: their boxes are shown above the page. The watermark is still on the page beneath them.
• A file says "Locked with a password". It needs a password to open, so it can't be used here. Unlock it first, then add the unlocked copy.
• "These files are too big to handle in this browser's memory." Stamp fewer files at a time, or use a computer, which usually has more memory than a phone.

Limits

• A label, not protection. Anyone with PDF editing software can remove a watermark. It doesn't stop opening, copying or printing.
• Latin letters only for words. The standard bold font has Latin letters, with accents, digits and common punctuation. For other scripts, make a picture of the words and use it as a picture watermark.
• One line, one font. Words are one line of Helvetica Bold, in grey, red, blue or black.
• On top of the page. The watermark is drawn over what is on the page, not behind it. At a low opacity this looks the same as a mark behind the page on white paper.
• Added for good. The watermark can't be taken off again here. Keep your original, which is never changed.
• Locked and signed files. A PDF that needs a password to open can't be used until you unlock it, and a digital signature isn't valid on the changed copy.
• Memory. We set no size or page limit, but the file has to fit in your device's memory. Phones have less than computers, so very big files are easier on a computer.

Watermark terms, explained

Watermark

Words or a picture shown faintly across a page. The name comes from paper makers' marks, pressed into paper while it was wet.

Opacity

How solid something is drawn: at 100% it covers what is under it, at 30% most of the page shows through.

Transparent PNG

A PNG picture whose background is see-through, so only the logo itself shows when it is placed on a page.

Point

The unit for the size of type: 72 points make an inch, or 2.54 cm.

Helvetica Bold

A plain, heavy font that is one of the standard fonts every PDF reader has, so a PDF can use it without carrying a copy.

Digital signature

A coded seal that shows who signed a PDF and that it hasn't changed since. A changed copy no longer carries a valid one.