If you are testing say the Rocket Rides app with an actual reader (i.e. on an actual device), you'll need to modify web.rb to prompt sinatra to bind the server to more than just localhost (the default).
Please add this to the README, i.e. to do something like this:

If you are testing say the Rocket Rides app with an actual reader (i.e. on an actual device), you'll need to modify
web.rbto prompt sinatra to bind the server to more than just localhost (the default).Please add this to the README, i.e. to do something like this: