Hi,
A relatively simple request: please allow me to search your database using my mobile device, similar to what is possible on the desktop website.
On the desktop, I have “Advanced Search” available, which allows me to search by key, among other options. That alone would be perfect, as I would love the ability to browse all songs in a certain key while I’m commuting for inspiration.
Or I am just blind and I can’t spot the feature on the mobile page. 
Love Hooktheory overall tho! 