Every tool here can be installed like an app. It then opens from your home screen or dock, works with no internet, and keeps working if this website ever goes away.
Each tool installs on its own, so you can install just the one you need, or install the main page to get all of them.
Your work is saved on your device, not on a server, so nobody else can see it and nobody can recover it for you if you delete it. Save or send yourself the PDF when you finish.
On an iPhone use the Airplane mode check instead. Safari on iOS has no network panel.
There is no account and no sign in, because there is nothing to sign in to. Your documents are opened by your browser and stay in it.