Versions

For more recent release information, refer to the [[JavaScript Office Add-ins]] page

NAPA Online 2013

Released: August 2013
Content Apps could contain multiple pages
Mail Activation Rules Editor
Task Pane - Excel 2013, Excel Online
Task Pane - Word 2013
Task Pane - PowerPoint 2013
Task Pane - Project 2013
Content - Excel 2013, Excel Online
Mail - Read Form: Email and Appointment, Outlook 2013, Outlook Online, OWA for Devices

NAPA Online 2012

Released: August 2012 only for Excel

link - learn.microsoft.com/en-gb/archive/blogs/officeapps/use-napa-office-365-development-tools-to-build-apps-for-office-and-sharepoint-on-the-browser 

Required an Office 365 Developer Account
Create an Office Add-in just using a Browser
Focused more on SharePoint Apps
You could open a copy in Visual Studio 2012 RC
Task Pane - Excel 2013
Task Pane - Word 2013
Task Pane - Project 2013
Content - Excel 2013
Mail - Read Form: Email and Appointment, Outlook 2013, Outlook Online

xlmns = "http://schemas.microsoft.com/office/appforoffice/1.0" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"