The two best plugins available for WooCommerce PDF file download watermarking/passwording are WooCommerce PDF Watermark and PDF Ink (sold here). If you’re considering purchasing one or the other, this post will help show you which is the better choice.
Both plugins have been available for many years, both plugins perform the same essential tasks, and yet they are quite different under the hood. They offer different features, and at different price points.
- The bundled software
- Feature comparison
- Image watermarking
- Available fonts
- Watermark opacity
- Watermark locations on the page
- Pages to watermark
- PDF security
- Barcodes
- Product-by-product settings
- File management
- Missing features
- Plugin price
What’s under the hood:
Both plugins use free, open-source PDF manipulation libraries to accomplish passwording and watermarking.
WooCommerce PDF Watermark uses FPDI to parse PDFs and FPDF to re-write them.
As of October 2023, WooCommerce is using version 2.36 of FPDI, released in February 2021. Version 2.5.0 is available, released September this year. This means not only could their parser be faster, but might also be missing security fixes. The plugin uses version 1.8.4 of FPDF, released August 2021, when version 1.8.6, released June 2023 is available.
If you are here because your WooCommerce PDF Watermark plugin is broken, write to us for more details – we are happy to advise.
As of Spring 2025, WooCommerce PDF Watermark has started using our customized, namespaced TCPDI libraries instead of FPDI + FPDF. We are flattered? Maybe that tells you everything you need to know, but if not, please keep reading!
PDF Ink can use FPDI + FPDF, but it can also use other libraries like TCPDI, TCPDF, FPDI-PDF Parser, and SetaPDF Stamper. It is designed to be flexible. So if your PDF isn’t happy with one parser, you can change parsers and try again. The free parser sets included with PDF Ink are TCPDI+TCPDF, FPDI+TCPDF, and FPDI+FPDF. Purchase of PDF Ink comes with a 20% discount toward the purchase of FPDI-PDF Parser and/or SetaPDF-Stamper. These advanced libraries allow for handling of PDF files with advanced features such as forms, layers, and internal links/table of contents.
Feature Comparison
Image watermarking
Adding an image to an existing PDF is a feature of both plugins; however, PDF Ink allows you to do it anywhere amidst stamp text using an HTML <img> tag or by setting an image location in the settings panel.
The plugin PDF Watermark for WooCommerce does not allow HTML in watermarks. Lack of control with HTML tags such as <p>, <br>, <strong>, and <em> (to name a few) can be crippling for folks who want to “design” their watermark. Our plugin allows the use of most common HTML tags in watermark text, translated straight onto the page!
Fonts
Both plugins come with core fonts offered by their respective PDF manipulation libraries (FPDF/TCPDF). However, PDF Ink allows the administrator to add their own TTF font files so that watermarks can match branding. That means our plugin allows the user to watermark with nearly any font, not just Times, Helvetica, or Courier. Our plugin offers better support for non-English languages, since it also includes different subsetted fonts straight out of the box.
Watermark Opacity
Both plugins allow watermark opacity to be set lower. PDF Ink does this using a shortcode, allowing for hundredth (.01, .02, etc.) increments and for some text to be transparent while other text is not, while the WooCommerce plugin sets opacity in the settings and it applies to the entire watermark.
Watermark Locations
Both plugins offer similar options for placing a watermark anywhere on the page; however, WooCommerce’s offers only one watermark location whereas PDF Ink allows for many watermarks per page. This could allow the administrator to apply two visible watermarks and one tiny invisible watermark, which would increase security, and the potential thief’s paranoia. Hidden watermarks — not visible ones — are perhaps the best way to track PDFs and thwart/fight intellectual property theft. Both plugins would allow hidden watermarks, but with the two placements our plugin allows, it’s easy to make the customer think there’s only one watermark, when in fact there are two!
Our RTL setting is not only handy for RTL languages, but also for aligning marks faithfully along the right margin, such as is useful in marking sheet music.
Pages to Watermark
WooCommerce PDF Watermark allows the administrator to set pages to “All,” “First,” “Last,” or “Alternate”. PDF Ink allows watermarking to start on a specified page (e.g. page 2), end on a specified page, and beyond that allows “All,” “First,” “Last,” “Odd”, or “Even” pages to be watermarked. Custom pages can be set, such as “1-4,6,8-10” where pages 5 and 7 would not be marked. Furthermore, filter hooks are available to exclude specific pages in a range. WooCommerce does not allow that.
With PDF Ink, you get a lot more control of which pages are watermarked.
PDF Protection
WooCommerce PDF Watermark allows RC4-128 encryption for PDFs, with the basic four PDF protections of “Disable Print,” “Disable Copy”, “Disable Modify,” and “Disable Annotate”. Arcfour (RC4) encryption is generally accepted as being weak, and so these days if your server can handle it, you want to be using AES encryption for your PDFs.
AES is possible with PDF Ink. AES encryption of PDF offers the four basic PDF protections, as well as more advanced protections like “Disable High-Resolution Printing,” “Disable Assembly,” “Disable Form Filling,” “Disable Accessibility”.
Both plugins allow for using the customer’s email as the PDF password. WooCommerce’s offering also allows using the Order ID as a PDF password, but we’re not sure the use cases of that, since order numbers are difficult to remember or find. PDF Ink allows for an owner password to be reset, and for the option of a user password to become the owner password, essentially handing over the keys to a PDF to the purchaser. These options might have a limited use case, but they’re available. Overall, our encryption and passwording is much more robust than WooCommerce’s.
BARCODING
We have it, they don’t. Read more about adding barcodes to existing PDF files.
Product-by-product plugin settings
WooCommerce’s plugin offers the option to override the watermark content (text/image) or turn watermarking off per product. It does not allow for different watermark settings between product variations.
Our plugin offers FULL override per product, such that if you want a different PDF product to have a totally different content, placement, font, opacity, content, password, and encryption level, that is possible.
PDF Ink also allows full override per product variation, not just per product!
File management
What happens to the PDF files when they’re being manipulated just before delivery, and after delivery? This is a mystery most people don’t spend much time thinking about, but these files can amass and cause problems if left on the server.
WooCommerce’s offering sends altered PDFs to a file with a changed filename into its original folder, yet has no settings or means to send elsewhere or clean up afterward.
PDF Ink sends out PDFs depending on the type of WooCommerce download (in Woo downloadable product settings). If it’s a forced download, no file is stored on the server. Otherwise, files are stored separately in the wp-content/uploads/ directory in a unique folder which can be perused in a meaningful way, since sub-folders are named by customer order number. Furthermore, the plugin includes settings to clean up these files by CRON if desired on a “hourly,” “twice daily,” “daily,” “weekly,” every 15 day,” or “monthly” basis. They can also be left on the server if that is preferred.
When the file is delivered, our plugin does not change the filename. The customer gets the PDF with its intended file name, unless you decide to change the name using filter hooks.
Additionally, if you would like to save on bandwidth, PDF Ink has a unique setting to allow previously watermarked (and stored) PDF files to be re-delivered on customer request, instead of going through marking again (which can be CPU-intensive). We call this recycling.
Features missing in WooCommerce’s offering:
- Does not handle PDF versions 1.5, 1.6, or 1.7
- Only one watermark location
- Only one image watermark
- No HTML in watermarks
- No custom fonts
- No RTL watermarking
- No barcodes or QR codes
- File name and placement management
- No RC4-40 or AES encryption levels
- Per-product settings do not have full settings override, or variation override
- Ability to handle more complex/sophisticated PDFs, such as those with fillable forms, layers, incrementation, or web-optimization
Features missing in PDF Ink:
No ePub watermarking(EPUB watermarking added June 2025)
If you need complete fidelity, please use the ONLY plugin capable of handling ALL PDFs: PDF Ink (upgraded with the 3rd party SetaPDF Stamper library).
The price
Our plugin has always been priced about $10 lower than WooCommerce’s offering, despite offering more features. Currently WooCommerce charges $99, while we charge $69. This is impossible to explain. Just enjoy it!
Ultimately, we find that in the case of WooCommerce’s offering, you pay more but get less. Heck! The free version of our plugin offers many of the same features as WooCommerce’s $99 plugin!
We welcome you to try out PDF Ink with no risk. We offer a 30-day no questions asked refund policy for the paid version, and priority email support!