Goals: Add links that are reasonable and good explanations of how stuff works. No hype and no vendor content if possible. Practical first-hand accounts and experience preferred (super rare at this point).
If you, like me, resent every dollar spent on commercial PDF tools,
you might want to know how to change the text content of a PDF without
having to pay for Adobe Acrobat or another PDF tool. I didn't see an
obvious open-source tool that lets you dig into PDF internals, but I
did discover a few useful facts about how PDFs are structured that
I think may prove useful to others (or myself) in the future. They
are recorded here. They are surely not universally applicable --
the PDF standard is truly Byzantine -- but they worked for my case.