PDF Watermarking Limitations, explained

Update March 2020: PDF Stamper (a separate plugin from Waterwoo PDF Premium) now allows PDF owners to keep their PDFs exactly as they are, but add a stamp. PDF Stamp is a drop-in plugin and requires users also purchase SetaPDF-Stamper software to install alongside it. Learn more here.

WaterWoo is magic, but it does have its limitations. And one particular limitation has been disappointing customers, and frustrating us, for years. We'd like to explain.

First of all, let's explain how WaterWoo works. In a nutshell, WaterWoo works by first reading a PDF into memory, then spitting it back out onto the page with watermarks rolled in. If the parser (FPDI or TCPDI) which reads the PDF does not read all the PDF, or cannot read certain PDF versions, then WaterWoo fails to deliver the expected. Ultimately, WaterWoo is built on top of 3rd party software, and there are factors we cannot control.

We are unaware of any PDF watermarker for WordPress available which preserves all PDFs in their original form while parsing them. This is due to prohibitive licensing by . Folks continue to ask for this feature -- constantly -- however, none have the budget to develop it, and we cannot develop it free, knowing end customer interest is still low. Here is a history of where we have been with this issue over the years.

WaterWoo was originally built to watermark PDF versions of sewing patterns. These sewing patterns did not have any extended PDF features; they were simply meant to be printed. And we wanted a watermark on them to help preserve our intellectual property.

WaterWoo was originally constructed with the free FPDI and FPDF libraries, which in their free, open-source (MIT) versions have limitations. These are:

  • PDFs newer than version 1.4 are not parse-able and therefore not watermarkable (FPDI)
  • Advanced PDF contents such as forms, annotations, and table of contents (internal links) are not preserved (FPDI)

The developer of FPDI offers product to correct these limitations; however, their pricing and/or licensing are prohibitive. Originally, WaterWoo PDF Premium used 's FPDI PDF parser to include PDFs 1.5 and newer -- such a critical and obvious move. When the author of bumped us (and our competitors) off our licenses in late 2016, we turned around, refactored, and released the massively improved WaterWoo PDF Premium 2.0, which was built on GNU-compatible libraries TCPDF and TCPDI. As we understand it, WaterWoo PDF Premium is the only WordPress watermarker built on GPL-compatible software, and which respects other developers' licensing terms. Another way of saying this, is if you find a perfect watermarker, it's likely the author has significant capital and/or is violating license terms. We think that violation is really... uncool.

WaterWoo and EDDiMark have more features than any other watermarker for WordPress, hands down. However, this limitation remains:

  • Advanced PDF contents such as forms, annotations, and table of contents (internal links) are not preserved.

We have agonized over this for years now, and have decided to stop. It is possible that as the code evolves, these features might fall into place without us having to spend extraordinary time and money which we cannot find. It's important to remember that WordPress plugins and other software does not magically arise from the ether. Smart, focused human beings write the code, and deal with support and feature requests, and this takes a lot of time and careful attention. We'd like to focus on keeping WaterWoo stable and functional, and provide you excellent support.

So, bottom line: you won't find this feature by searching around; you'll find it with a lot of time and money. For folks who insist on having their cake and eating it, too, we recommend you watermark your PDF using Acrobat BEFORE selling it, and forgo WordPress PDF watermarking.

Thank you for your understanding.


(Having cake and eating it too is a great thing!)