Introduction to Office 365 Development

http://www.microsoftvirtualacademy.com/training-courses/introduction-to-office-365-development?m=10072&ct=31602

Developing on the Office 365 platform

http://msdn.microsoft.com/en-us/office/office365/howto/platform-development-overview

Set up your Office 365 development environment

http://msdn.microsoft.com/en-us/office/office365/howto/setup-development-environment#bk_Office365Account

Start with a free 30-day trial account

https://portal.microsoftonline.com/Signup/MainSignUp.aspx?OfferId=6881A1CB-F4EB-4db3-9F18-388898DAF510&DL=DEVELOPERPACK

log into the developer site

https://login.microsoftonline.com/

OAuth2 in action with the release of Office 365 Calendar, Contacts and Mail

http://blogs.msdn.com/b/exchangedev/archive/2014/10/28/oauth2-in-action-with-the-release-of-office-365-calendar-contacts-and-mail.aspx

Office 365 REST APIs reference

http://msdn.microsoft.com/office/office365/APi/api-catalog

Calendar REST operations

http://msdn.microsoft.com/office/office365/api/calendar-rest-operations

 Office Developer Tools for Visual Studio 2013

 https://visualstudiogallery.msdn.microsoft.com/a15b85e6-69a7-4fdf-adda-a38066bb5155

 Office Developer Tools for Visual Studio 2012

office365 development