Add a watermark to a PDF

How to use it#

1. Drop a PDF onto the box above, or click it to choose one.
2. Choose Text and type the words, which start as CONFIDENTIAL, or choose Image and pick a logo or picture.
3. Pick the opacity, the angle, once or tiled, the size, and, for text, the colour. The preview updates as you change them.
4. Download the watermarked PDF. The original is left as it was.

What a watermark is for, and what it is not#

A watermark tells anyone holding the document what it is: a draft that should not be quoted, a copy sent to one person, a confidential paper that should not travel further. It travels with every page, including printouts and screenshots, which is what makes it worth adding.

It does not stop anyone reading or changing the document. The watermark is added to each page as text or as a picture, and someone determined, with an editor and some patience, can find it and remove it. If the document must not be read by the wrong people, protect it with a password as well, which the password protect tool does.

Choosing how it looks#

Diagonal is the classic look and the hardest to crop out of a screenshot, since it crosses the middle of the page from one corner to the other. Level text reads more quietly and suits a stamp such as COPY or SAMPLE. Either way, it is centred on each page as the reader sees it, so landscape and rotated pages come out right.

Tiled repeats the watermark small, in staggered rows over the whole page, the way stock photos and bank statements are marked. One mark in the middle can be cropped out of a screenshot or covered with a box; a tiled one is on every part of the page, so any piece taken from it carries the mark. Size then sets how small each copy is, and Spacing how far apart they sit: Wide keeps a busy page readable, and Close leaves no gap a paragraph could be lifted from.

Opacity decides how see-through the watermark is, and so whether the page underneath is still comfortable to read. Around a quarter is visible on every page without getting in the way of the text; go higher for a document that will be printed on a poor printer, and lower for one that will be read closely on screen.

Using a logo as a watermark#

A logo marks a document as coming from you in a way a word cannot, and it is what most people want on a quote, a report, or a portfolio sent to a client. Choose Image and pick the logo. The angle, the size, and the opacity work as they do for text: Large lets the logo reach most of the page, Level keeps it straight, and a low opacity lets the page read clearly through it.

A PNG with a transparent background gives the cleanest result, because only the logo itself is drawn. A JPG has no transparency, so its white or coloured background is drawn too, as a faint rectangle; if your logo only exists that way, the background remover can turn it into a transparent PNG first. Colour applies to text only, since a picture keeps its own colours.

What changes in the file#

A text watermark is drawn on top of each page in Helvetica, a font every PDF reader has built in, so no font has to be embedded and the file grows by a couple of hundred bytes a page. The page underneath is untouched: text stays selectable and searchable, and links keep working.

A logo is stored in the file once, however many pages it appears on, so a 40 KB logo adds about 40 KB to the download. A JPG or PNG goes in exactly as it is, with nothing compressed again, and a photo taken on a phone is turned the right way up. Any other format is converted to PNG first.

The built-in font covers English and the other Western European languages, with the usual symbols. Letters it cannot draw, such as Greek, Cyrillic, or Chinese, are named in a message rather than dropped, since embedding a font for them would add a large file to every download. Words inside a logo are part of the picture, so they have no such limit.