FXB is an extension given to files used by software from Steinberg Media Technologies GmbH. FXB files are used to store audio plug-ins used, among others, by a program such as DAW, Cubase. Such a file allows you to increase the sound capabilities of the program. Most often these are color sets of sounds. It is a file saved in the VST standard.

Currently, the FXB format is rarely used and is considered obsolete, and plug-ins are stored in VST files used not only by Cubase but also by other digital audio workstations.