.FMX File Extension
What is an FMX file?
An FMX file is a plug-in used by the Windows version of FileMaker Pro, a database program. It contains information that expands the capabilities of the FileMaker software, such as automating certain functions.
When you install plug-ins to FileMaker Pro, the FMX files are placed in the "Extensions" folder, which is located in the FileMaker directory:
Windows Vista, 7, 8, & 10:
NOTE: If you use the macOS version of FileMaker Pro, the plug-ins are contained in .FMPLUGIN files.