I'm finding THIS piece of software quite useful.
Wavemaker Cards
It is actively supported and V4 is in beta at the moment. V3 is stable.
It is free, and it runs on virtually anything that can use a Chrome browser. It isn't a cloud-based web app, exactly, it is a Progressive Web App. Which, as I understand it, is a locally resident program that uses much of the Chrome infrastructure to operate, but does not need to be 'online' to work. It doesn't import at all. So you need to start using it with a new project.
It stores data on Google Drive and on the local drive. In short, it can cater to almost any hardware/software prejudices you might have.