Add Watermark to PDF Online – Text or Logo on Every Page

Add a watermark to a PDF without installing anything

A watermark is a line of text or a small picture stamped onto the pages of a document so that anyone holding the file knows what it is: a draft, a copy made for one named person, a confidential report, or something that belongs to your business. Jobsixo lets you add a watermark to a PDF online in a few seconds. Type the wording or add a logo, choose where it sits and how faint it is, preview the first page, and download the stamped file.

It suits a freelancer sending a design proposal that is not yet approved, a coaching institute putting its name across study notes, a consultant marking a report CONFIDENTIAL, and anyone who has to hand over a photocopy of an ID and wants it tied to one purpose. If you were searching for a way to stamp confidential on a PDF or to put a logo watermark on a PDF without paying for desktop software, this is the whole job.

How to add a watermark to a PDF

1. 1
   Drop the PDF onto the box, or click it to browse. You can add several PDFs at once and each one is stamped the same way. If you want a logo instead of words, add a PNG or JPG alongside the PDF.
2. 2
   Type your wording in Watermark text (ignored if you add an image). The box starts with CONFIDENTIAL.
3. 3
   Choose the Font (Helvetica, Times or Courier), the Weight, the Font size and the Text colour (hex). The starting values are Helvetica, Bold, 48 and #7f7f7f.
4. 4
   Pick a Position from the nine on offer, then decide on Mosaic (one stamp per page, or tiled across the whole page) and Layer (over the page, or underneath it).
5. 5
   Set Rotation (degrees) and Opacity (0 to 1). The defaults, 35 and 0.18, give a faint diagonal stamp.
6. 6
   In Pages, leave all, or type a list such as 1,3,5-8.
7. 7
   Press Preview page 1 with these settings and adjust until it looks right. Then press Add Watermark and download watermarked.pdf from the list that appears.

Every watermark setting explained

The page has more controls than most free watermark tools, so here is what each one does and where it starts.

How the watermark is drawn

The file is opened in your browser with pdf-lib, an open-source PDF library. For a text watermark the tool picks one of the three standard fonts that every PDF reader already contains, measures how wide your wording will be at the chosen size, and draws it onto each selected page with the opacity and rotation you set. An image watermark is embedded once and placed on each page at the width you gave, with its height worked out from the picture's own proportions.

The stamp is real page content, added as an extra layer of drawing instructions. With Layer set to Underneath, that layer is moved to the front of the page's list of instructions, so the original content is painted over it. Nothing is flattened or re-encoded, which is why the original text stays selectable and form fields keep working.

One detail affects placement. Rotation turns the stamp around the start of its text, not around its middle. A tilted stamp set to Centre therefore lands higher and further left than a flat one would. The preview button exists for this reason.

A worked example with real numbers

Take an A4 page, which is 595.28 by 841.89 points (210 by 297 mm, with 72 points to the inch). In bold Helvetica at 48 points, CONFIDENTIAL measures 357.3 points, or about 126 mm. Laid flat it would leave roughly 119 points of paper on each side.

Opacity 0.18 with the default #7f7f7f colour means 18 per cent of the grey is mixed with 82 per cent of white paper. Each colour channel works out as 255 minus 0.18 times (255 minus 127), which is 232, a light grey that sits behind text without hiding it.

Now the tilt. At 35 degrees and Centre, the middle of the word ends up at about 256 points from the left edge and 513 points from the bottom, against a page centre of 297.6 and 420.9. That is about 42 points left and 92 points high. If you want the stamp visually centred, preview it and try a different Position, or set Rotation to 0.

Tiling follows its own arithmetic. DRAFT in bold 48 points is 162.6 points wide. The mosaic steps across by 1.45 times that width (235.8 points) and down by three times the font size (144 points), starting 36 points in from the left and bottom edges. On an A4 page that gives three columns and six rows, so 18 stamps per page and 180 across a ten-page file.

Reading the result

When the job finishes you see Done with one file and a one-line note such as Text watermark on 12 page(s), tiled across each page, underneath the existing content. Check the page count in that note against what you expected from your Pages entry. The file is called watermarked.pdf, has the same number of pages as the original, and the page sizes are unchanged.

Size grows only a little. In a test on a plain 12-page file of 12,646 bytes, a single CONFIDENTIAL stamp took it to 15,873 bytes and a tiled DRAFT to 21,747. Each stamp is a few drawing instructions, not an image of the page.

Where a PDF watermark earns its place

• Drafts and quotations that are not final: DRAFT or NOT FOR SIGNATURE across a rent agreement, tender document or proposal.
• Photocopies of identity documents. Many people in India tile a line such as FOR KYC WITH ONE BANK ONLY, with the date, across an Aadhaar or PAN scan before emailing it, so the copy is hard to reuse for anything else.
• Sample question papers and chapter excerpts from teachers and coaching centres, marked SAMPLE or carrying the institute's name.
• Client reports and audit working papers that should be read as confidential.
• Company circulars, price lists and brochures that carry a logo behind the text.

Tips for a watermark that works

• Stay between 0.10 and 0.25 opacity for a stamp over text. Higher than that and the page becomes hard to read.
• Keep the colour grey. A pale stamp prints well on a black-and-white printer; a bright one turns dark.
• Use Underneath for typed documents so the letters stay crisp, and Over for scans (see the next section).
• For ID copies choose Mosaic, a short phrase and an angle of 30 to 45 degrees, so no clean area is left to crop out.
• Limit the Pages box when a cover page or a signed final page should stay clean.
• Add the stamp last. If you also need page numbers, add them first, so the stamp sits on top of everything.

Mistakes to avoid

• Using Underneath on a scan. A scanned page is one picture that covers the whole sheet, so a stamp placed behind it is usually hidden.
• Typing Hindi or another non-Latin script. The built-in fonts cannot draw it and the run stops with an error. Make the wording into a picture and add it as an image watermark.
• Adding a JPG logo with a white background and then putting it over the text. The white box will show. Use Underneath, or lower the opacity.
• Running the tool twice on its own output. Each run adds another stamp, so go back to the original file when you want to change the wording.
• Treating the stamp as protection. It identifies a document; it does not lock it.

What this tool cannot do

Add several PDFs together and each gets the same stamp and its own download, named after the original. Files are limited to 100 MB and 500 pages. An encrypted PDF is refused, so unlock the file first if you know its password. The stamp has the same wording on every page, so it cannot print a different name on each page. It cannot remove a watermark that someone else added.

A watermark is also not tamper-proof. Anyone with a PDF editor can delete it, and a stamp near the edge can be cropped away. If the actual goal is to hide information, use the redaction tool, and if it is to stop a file opening, add a password.

Private by design, and what to do next

Everything happens in your browser tab. Your PDF is not sent to a Jobsixo server, there is no account, and no mark of ours is added to your pages. The preview is made from a one-page copy kept in memory on your device.

Once the file is stamped you may want to reduce the file size before emailing it, merge the files into one pack, or chain the steps so compressing, stamping and numbering happen in a single run. A logo in an unusual format can be prepared with the image converter first.