What are some alternatives?
When comparing Piano Academy and Simply Piano, you can also consider the following products
Flowkey - The easiest way to learn piano with your iPhone or iPad
Chroma - Welcome to Chroma Cutlery Cnife - Manufacturer of kitchen knives, includes products and contact information.
Pianu - Learn to play the piano in your browser.
Scale Search by Solfej - Searchable library of over 6000 different scales
Yousician - An interactive guitar-learning app.
Touch Pianist - Play piano like a pro without playing piano.