Get started with Office Add-ins (formerly Apps for Office)
An Office Add-in runs in an Office application and can interact with data in a document or mail item.
An Office Add-in is a web app that you can host anywhere. It runs in an Office application. A manifest.xml file specifies where the web app is located and how it should appear.
Choose the Office product you will build your add-in for
What development tool do you use?