Crosswalk
Has promise but falls short, literally
Yet when they updated that map to include the Second Avenue line, they somehow failed to notice that they were missing the #7 train's extension to 34th St.-Hudson Yards, which predates the Second Avenue line's opening!
This is all the more surprising because the developers claim to be New Yorkers who use the app themselves. I hope they will get back to work and apply the attention to detail the app deserves and requires.
Don't download.
There are other options.