You got a lot of critic here but feedback is good. I will try out your product. I am happy that its exits an an app and not web only. I don't know if this can "reboot" the internet or become a money making business. But looks interesting for sure.

What changed my life was recoll https://www.lesbonscomptes.com/recoll/

I also looked into OpenPaper but in the end it offers nothing that recoll does not and recoll does it better. https://openpaper.work/en-us/

Marking PDFs, make them searchable and adding comments in Polar could be great for grants and writing a thesis.

EDIT:

1. I really DO like the webcapture feature. I often save importent webpages since I know they may either not be available anymore in the future or I can't find the link anymore. This feature seems smooth already. But how can I sure that your software will still work in 10 years? Do you have an export feature already?

2. I would really like to be able to have folders as a feature to sort stuff better.

3. Your blog does not have an RSS feed.