Fm extension is associated with FileMaker Pro Document. You can try to open fm files with File Maker software.

These are the documents which created by FileMaker or FileMaker Pro. The file type of the new versions was changed as .fmp. 

FrameMaker : Framemaker software which is an Adobe product keeps file with this format.
To get detailed information about filemaker or framemaker software, please check the following links.

What to use fm

File Maker or File Maker alternatives

which page related to fm file

fm Related Searches

You can check related links about fm fileextension.