You're being downvoted because not everyone has CLI access to a server and the required ghostscript binaries etc.

Realistically, most 'normal users' have PDF needs like these links and we as tech people can safely give these sites to non-technical people and have confidence their data isn't being stolen on remote dodgy servers (think gas / electricity bills, invoices, bank statements etc which is a PII gold pot).

Server? what server? Ghostscript is available in virtually any Linux distro, on Mac with and without brew and even on Windows.

I have no confidence in any website, especially the one that claims to be local-only but can technically change on a whim of the developer once it starts getting enough traffic from users.

OTOH, I trust 30+ years old software sitting on on my hard drive not to phone home on every keystroke.