Hey Parker, check out this thread:
I have a free key of Systweak PDF Editor tool for edit, convert, compress your pdf file safely and easily.
I’m not sure if this is a good option…
I checked their website and the price is around $100USD per year.
Also, it’s not even open source… 
EDIT: I’m surprised nobody has mentioned Sumatra. It’s free and open source and even comes with a portable version:
It also has a very active community if you need help:
EDIT 2:
The sourcecode is even available.
The portable may be of use to you as it can be run from a USB drive without installation or making any changes to the Registry
isnt sumatra just a PDF reader and not an editor?
It can work as both.
It lists the editing functions here: SumatraPDF documentation
I thought it’d be a great suggestion because of its features that are inline with this community: open source, minimalist design and portable version.
I take it PDF XChange Editor is not recommended?
also for editor I recommend Xodo on android, just don’t allow internet to it 
if you have some conscerns you can always cut the oxygen i.e. just disallow it in the firewall
technically speaking and features-wise I’m yet to find a better editor than PDF XChange (for my Windows machine). I just cut off all it’s connections to the internet cause it’s most probably not private at all.
You mean you cut it’s connections via firewall or how?
If you don’t need advanced features Firefox built-in pdf editor is quite nice and with the latest release it got also notes support.
Do you trust a browser (even FF) to not send any PDF info or data over the internet?
I actually do, more than some random pdf editor.
It is constantly updated with the browser, it’s somewhat sandboxed and I don’t need to install a third party software and audit it, keep track with his development and updates.
If you already trust your browser for all the internet surf I don’t see why you shouldn’t for pdfs.
yes, firewall.
PDF24(.)org
BentoPDF.
Online or self-hosted
I appreciate your replies, but what makes these ebook reading solutions so secure and how do they prevent personal user information being sent back to the Internet to someone?
I appreciate your reply!
Somehow I only just came across your post now. I think this is the best idea I’ve come across?
Which firewall do you recommend?
On windows? The hosts file or if you are lazy portmaster though they don’t have arm64 last I checked
I’d recommend Files Editor if you want a PDF editor that puts a good amount of emphasis on security. According to their T&C, files are handled with encrypted storage, and it includes privacy-focused tools such as password protection and permanent redaction of sensitive information. It’s also fully browser-based, so there’s no desktop software or browser extension to install.