Although with desktop and paid software it is trivial to add a watermark to a PDF document, they are not always available, particularly, because you do not even have access to the documents from the same computer.

Well, to solve this problem, today we will review 4 simple and free online options with excellent results when performing this necessary task. Of course, before pointing them out, it is worth mentioning that watermarks are floating signs that are added to documents, just like digital signatures, to minimize the possibility of copying or improper distribution by third parties.

1. PDFaid/Watermark

PDFaid is a collection of tools for converting file formats to and from PDF as well as for compression, image extraction, renaming, merging, splitting and, of course, adding watermarks to such documents. A quick editor there will allow you to choose the watermark text, font, font size, style, rotation, position and transparency.

2. Very PDF/stamp

Another useful collection of online tools that involves even invoice generation, website to PDF conversion and options for resizing PDF files. For watermarking it offers options to upload a PDF locally or from a URL along with a quick editing panel also with functions to define the text, rotation, font, style, location, opacity and even its color.

3. Watermark PDF Files/Watermark

A third collection of tools for working with multiple formats including PDF documents. It is almost a clone of the first service but with a more discreet distribution of options, but the same ones already mentioned: watermark text, size, font, style, position, transparency, etc. You only need to click on Watermark PDF to run the conversion process and a small pop-up window will generate the link to the file with the watermark.


Don’t be confused by its simple appearance (just two buttons) because what it offers, in terms of control and capacity, turns out to be a worthy opponent to the previous services. The idea with this tool is to previously create a PDF file that only has the watermark (even with Microsoft Word you can design it saving the results in PDF format) and the following will be to load two files to, the file with the created watermark and the PDF that you want to mark; The magic of the service is to combine them automatically and properly.


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