Current work in progress for the offline HTML5 hybrid app, please try it: https://checkvist.com/auth/mobile
We also have a separate feature pool for it:
This seems like a decent application, but the lack of native support for Android kills it for me. It is absolutely essential for me to be able to access my notes on my phone. Other outliner applications like Workflowy and Moo.Do both have this feature. if you want to compete on the market you need to develop a mobile app.