There's a ton of PDF forms that I deal with at work that only work with Adobe Acrobat. When I open them in other PDF viewers, it'll be a single page telling me that if the PDF doesn't load in a few seconds then my PDF viewer is not compatible with the document.

I'm not an expert, but I imagine that they were created with Acrobat and it embeds some (proprietary) stuff in the PDF that only works with Acrobat. Acrobat is also the only PDF client that I'm aware of that supports signing PDF forms with certificates. There's other features in some PDFs that I've encountered that'll only work in Acrobat as well, like buttons embedded in the PDF to email the form or dropdowns in the form that don't work in other viewers.

It seems pretty swampy to me when 90% of the PDF forms I deal with can only be (fully) completed in Acrobat.

I’ve never come across this. What kind of business?

Using JavaScript, it's easy to create a standards-compliant PDF with inconsistent behavior in popular viewers. For example,

  https://jasomill.at/HelloGoodbye.pdf

contains JavaScript that, per the spec, should display a pop-up alert ("Hello Acrobat <version>") when it is opened and another ("Goodbye Acrobat <version>") when it is closed.

Actual behavior is inconsistent. On my Mac:

Acrobat: both alerts display

Preview, Safari: neither alert displays

Chrome, Edge, Firefox: only open alert displays

But it became successful long before it stopped being a vendor-locked swamp.

I can't recall a time when the PDF spec wasn't open, or at least openly available.

From 1993 to 2008?

Hmm...it wasn't an ISO standard, but the standard was freely available both as a download from the web-site and as a book.

My printed copy (version 1.4) is from 2001, and that's a later version, I definitely had earlier, much slimmer books.

The 1.0 PDF reference on Adobe's web-site has a Copyright of 1993 and says "First Printing, June 1993".

https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandard...

And of course there were multiple unlicensed implementations. Famously, Apple switched from Display Postscript in Rhapsody and Mac OS X Server to Quartz and PDF in Mac OS X to remove the DPS licensing costs.

Color me skeptical. PDF viewing is reasonable, but where are the decent PDF editing tools? I’ve looked, and it seems like nobody else but Adobe is allowed to do real PDF editing. Many many third part apps claim to, but only do superficial editing and don’t remotely match Acrobat tools. I don’t know how the API licensing works, but I imagine this makes sense because the real market for PDF is business documents that involve signatures, watermarks, password security, versioning, maybe some tracking, etc..

PDF manipulation is IMHO a niche application. If one really has to do that at scale, it would be probably better to fix the problem upstream to generate it correctly in the first place, or to layer the changes on top of the existing PDF and sign it.

That’s like saying image, audio, or video editing is niche. The number of PDF editing apps online suggests you might have formed an opinion before doing any research? Apparently lots and lots of people want to edit PDF files, enough that there’s a ton of competition. Why do you assume editing a PDF means the file is somehow incorrect, or that there exists any viable upstream solution? It’s more likely the edits are intended to make a new version, and don’t even belong upstream, and that editors have no access to upstream anyway. In addition to editing, there’s a whole industry of scraping PDF publications for data.

Yeah, I admit this was a risky statement :-)

Editing the PDF just seems like the wrong place to place the edit since it is a format intended for interchange and archivation.

Layering changes on top makes total sense. Changing existing objects seems fragile. But maybe I feel that way because the format is known for being so complicated and bespoke that only Adobe's tools can edit it reliably. Just about any document format which can be converted to PDF is easier to edit, therefore it would make more sense to apply changes before conversion to PDF, if at all possible.

I agree that reading and scraping PDFs on scale is a very common operation.

It is easier & better to edit before baking to PDF, that is true.

I know you're talking about GUI editing, but I've found libqpdf[1] incredibly useful for making programmatic PDF edits with minimal (typically no) structural disturbance.

[1] https://qpdf.sourceforge.io

Thanks! I’m checking this out.