Honestly, you should charge like $1 for each operation. People will trust it more that way, as you're not incentivized to snoop on their files (or put 500 ads everywhere).
Ah yeah, the surefire way of getting "trust" is by charging people, how could one forget about this obvious way...
Also, how would charging work when you're offline? One of the features of the tooling is that stuff works offline, seems maybe charging for each use wouldn't quite match up with reality.
In general, I have been thinking about how to get some earnings from this, it would allow me to spend more time and continuing to improve the tool faster. I am still not sure the best way to do it without scaring away too many users. If I could get some earnings and also increase trust that would be great. Need to think about this idea, maybe I can do a test and see how it works out...
(I already ruled out ads, since I don't want to clutter the tool and also most ad networks are not exactly privacy friendly which one of the main ideas behind the tool)
I think you should be able to make some money by offering your services to corporations. They don't know that everything runs on the browser, but they will like and pay for the idea of adding this capability to their website (pdftools.acmecorp.com). Start with lawyers, I think they are prime customers (pdfux.biglaw.com). Once you explain to their IT that you are only leveraging the clien-side processing, they'll leave you alone. All they would do is give you access to a vps or a vm in their hypervisor, or heck you could dockerize and sell it branded to them(biglaw inc all over the place). I do believe that's called.. bespoke service!! lol.. and of course.. the annual support income.
I agree with selling to corporations. However, most big law lawyers will need a higher level of PDF functionality. At a quick glance, I notice that the tools can't manipulate bookmarks, which are required for electronic filing in most courts.
Also, how would charging work when you're offline? One of the features of the tooling is that stuff works offline, seems maybe charging for each use wouldn't quite match up with reality.