The .fxp files are files created with the use of Flash Catalyst or Flash Builder. Files with the .fxp extension are often called project files because they are mostly created by Web developers as projects for their clients. This is because the main function of this software is to help users in creating Web applications and other items usually found in websites. These project files normally contain design elements like buttons, codes and other formulas needed to create a website. Project output files that can be created with this software are in the .fxp format. Files with the .fxp extension are also used by some VST audio plugins, and these files are used by any application that supports these VST plugins. These .fxp files are important to make audio files work the way developers of these VST plugins intended them to.