Windows 8 apps run in sandboxed environment where all direct communications between apps are prohibited. Instead, Windows 8 provides several mechanisms to facilitate indirect communications – protocols, file type associations and share contracts.

All these mechanisms allow transferring data between independent apps – in most of the cases developers don’t care about data source or destination. However, occasionally there is a need to support communications with a particular app. In this case all protocols, associations and contracts supported by target app need to be identified.

Declared protocols and file type associations can be determined through Control Panel:

• Search for Default Programs and open Set Default Programs screen
• Select desired app and press Choose defaults for this program

Unfortunately, Windows 8 does not provide any UI to discover share targets’ data formats. The only way is to go through manifest files for the installed apps and search for data format declarations. Some of these files are not well formatted so I decided to automate the task and created a small utility, AppXplorer:

This application lists all the installed apps and allows discovering supported protocols, file type associations, shareable data formats and file types.

You can download compiled executable or build it by yourself from source code (.NET 4.5/WPF).