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PDF

Foxit Reader

Foxit Reader is free, and despite its name allows basic annotations to a PDF document.

Installing

Foxit Reader can be installed with Chocolatey: 
choco install foxitreader
The following line installs Foxit Reader
  • without desktop icon
  • without default file association
  • without browser plugin and
  • without ConnectedPDF: 
choco install -y foxitreader --ia '/MERGETASKS="!desktopicon,!setdefaultreader,!displayinbrowser /COMPONENTS=*pdfviewer,*ffse,*installprint,*ffaddin,*ffspellcheck,!connectedpdf"'

Specifying a language

choco install foxitreader --ia '/MERGETASKS="!desktopicon /COMPONENTS=*pdfviewer,*ffse,*installprint,*ffaddin,*ffspellcheck,!connectedpdf" /LANG=en'
Note, although /LANG=en is specified, the installation executable is downloaded from an URL such as 
https://www.foxitsoftware.com/downloads/latest.php?product=Foxit-Reader&platform=Windows&package_type=exe&language=German&version=$version
This language=German seemed to ignore my request for an english installation, but the installer's source code has this helpful comment:
The "&language=German' parameter will force the download of "FoxitReader941_L10N_Setup_Prom.exe" containing all available languages.

Misc

Images can be added in the menu Home, with Image Annotation (on the far right side).

Unlocking secured PDFs

PDFs can be secured so that the cannot be edited anymore.
One way to make them editable is just to print them into another PDF document. However, this «solution» might blow up the size of the PDF (probably if it contains some raster graphics?). So, another way to remove this protection is to use qpdf (which can be downloaded from its releases page on github) like so 
C:\users\rene> qpdf.exe --decrypt secured.pdf unlocked.pdf

See also

okular
Xournal was helpful when I wanted to add images onto a pdf. (Tools -> Image)
pdfimages
pdftocairo uses the cairo output device of the poppler PDF library to convert a pdf into other formats: png, jpeg, tiff, post script, eps (encapsulated post script), svg, and again pdf.
Zanran is/has a tool to extract tabular data from PDFs
convert PDF to XML
Automatic Data Point Extraction
Perl module PDF::API2, Perl module PDF::Create
iText
muPDF promises to be lightweight and apparently comes with source code.
CutePDF: Convert to PDF documents on the fly
Saving a Word Document as PDF with Visual Basic for Application
The Open XML Paper Specification (aka OpenXPS or XPS?)
The Formula M function Pdf.Tables
A PDF file can be exported from Access under the menu External Data -> Export
The Excel VBA function range.exportAsFixedFormat() exports the data of the given range as PDF.
pdfgrep is a commandline utility to search text in PDF documents. This utility tries to be compatible with grep.
Adrianus Kleemans' blog post on Indexing PDFs with Tesseract (Tesseract is an OCR software).

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