Your writing stays on this device. Nothing is uploaded anywhere, and once Tacet has been open online for a few seconds, in the same place you write, it opens without a connection too. On iPhone, add Tacet to your Home Screen (Share → Add to Home Screen) and write only there: Safari can clear a site's saved data after 7 days without a visit. The Home Screen app and Safari keep separate copies, so what you write in one never shows in the other, and removing the icon erases its entries. Export a backup before you remove it, and now and then; use it to move entries to your Mac.