Are you looking to edit existing pdf documents, or create your own...
· Comment — Nicole Tedesco's post · View on Facebook · Markdown source
Are you looking to edit existing pdf documents, or create your own pdf documents?By "safe" do you mean "doesn't contain malware"? Or do you mean "nobody but me can read the documents"? LibreOffice Draw is probably the best open source editor for existing pdf documents: https://www.makeuseof.com/libreoffice-pdf-editor/ However, I find it munges the appearance fairly often. Unfortunately, there doesn't seem to be a better open source editor out there. If you want to create PDF's from scratch, I've been happy with LyX. https://www.lyx.org/ It's been developed for decades, so it's performance is solid. There are a bunch of other LaTeX editors which I haven't tried yet: https://medevel.com/20-os-latex/ If you just need the text, pdftotext might be an option: https://askubuntu.com/questions/52040/is-there-a-better-pdf-to-text-converter-than-pdftotext You might also find this script works well for you: https://globalblindspot.blogspot.com/2012/06/rudimentary-pdf-to-latex-conversion-in.html Note it depends on pdftohtml, gnuhtml2latex, and pdflatex being installed. If you don't mind using an online, non-free, proprietary tool, people report good results with mathpix: https://mathpix.com/ It will do up to 10 pdf pages per month for free. (But, they will be able to read your documents.)