Download the tools, products, and resources you need to create apps for Office and SharePoint.

Download the tools, products, and resources you need to create apps for Office and SharePoint.

You don't need to spend time downloading and installing software to get started. Office 365 for developers includes the tools and resources you need to start building and testing apps right now.

• SharePoint Online developer site
• You can install "Napa" Office 365 Development Tools, to create your first apps right within the browser
• Office Professional Plus 2013 including Excel, Outlook, Word, and Access
• Exchange Online 2013 server

For more detailed please go through the below mention link.

http://msdn.microsoft.com/en-us/office/apps/fp123627