admin We often use the Interop Tools tool to install apps from external sources. But there is another "specialized" tool for installing XAP files that is WPV XAP Deployer Tool. This is the difference and special point compared to Interop Tools. However, this tool is only supported on PC. Note: Your phone needs to have Developer Mode / Developer Unlocked enabled. Your computer needs to have the .NET Framework 4.5.1 installed. Download Net Framework 4.5.1 Download link: Windows Phone SDK 8.0 Lite. Download WP8.0 SDK Tools Lite here Windows Phone SDK 8.1 Lite. Download WP8.1 SDK Tools Lite here And WPV XAP Deployer Tool here. Steps to follow: Unzip the downloaded files. Open the WP8.0 SDK Tools Lite Setup Av1.0 folder and run the InstallWP8SDKToolsLite.bat file. Note: Do not run the file as an Admin. When the CMD window appears on the screen, press Enter. For all dialog boxes asking for confirmation, select Yes. After the process ends, you press Enter again. Do the same with the WP8.1 SDK Tools Lite Setup Av1.00 folder and InstallWP81SDKToolsLite.bat files. Unzip the downloaded files. Run InstallWP80SDKToolsLite.bat Instructions on how to install XAP file: Open the WPV XAP Deployer 2.0 folder and run WPV XAP Deployer. Select Add Xap. Now a dialog window appears on the screen, where you select the XAP file you want to install Then select Deploy and wait until the process finishes.