This page is for an offline DESKTOP/LAPTOP version, not mobile. To vote for a mobile app, see: https://noteflight.uservoice.com/forums/4962-tell-us-your-thoughts/suggestions/4327326-ios-and-android-apps-instead-of-accessing-throughTimothy Haynes commented
The main problem I have with the online version is not that it's online, but that it's incredibly slow! I'm working on almost a full symphony score--it's not even a full symphony-- and every individual note placement, dynamic change, text movement, basically each and every minute action takes at least 5 seconds to register. I have picked up on how to do work on about 3 individual actions at a time in the middle of every single lag spike, but it just keeps getting worse as my songs get more complex and longer. I know it's browser limitations, because I have a fantastic computer--not top of the line $5,000 or more, but still better than the average PC-- and this simple notation program lags like crazy!
It's incredibly annoying to write original scores when you have to wait for the program to catch up with your writing. It's time that actually makes me lose a lot of my creative thinking.
Comparing this to almost any other professional program, I can't believe anyone pays for such a slow creativity killer! And I think it's a problem that can be fixed by moving this software from the slow browser to it's own installed desktop program.