app.json is a manifest format for describing web apps. It declares environment variables, add-ons, and other information required to deploy and run an app on Heroku.| devcenter.heroku.com
Learn about the different generations of Heroku and associated features| devcenter.heroku.com
A technical description of the Heroku Platform API, which lets you programmatically automate, extend and combine Heroku with other services.| devcenter.heroku.com