Thanks for @rexrainbow & @gonzdevour . Your efforts on Parse makes C2 better and better!
Step 1. About Parse
------------------------------------
Parse© is an online backend app service which provides a shortcut for front-end web app developer to setup backend services. This is a very convenient way for web app developers to setup backend database without learning PHP & MySQL. In this tutorial we use Parse to setup a backend player info database which allows further login/sing-up operation.
Parse released its source code and turned to be an open project in Jan. 2016. In this tutorial we will teach you how to setup a private parse server on Heroku, and initialize Parse service in C2 project. Please note that you'll need a credit card number to validate Heroku account (no charge will be claimed, just for verification).
Step 2. Apply and setup your Heroku account
------------------------------------
Connect to heroku.com and click sing up to apply for an account.
Login to your account and you'll be brought to your personal apps page. You can find all your apps (projects) in the center list.
Next we are going to fill our credit card number. Click <Manage account> in the drop down list below your account name, select <Billing> tab in the center-top area, and select <Add Credit Card> to fill out your information. When it is done, your Heroku account is validated, and you can use all free Heroku services.