How to open .DEF file extension?

If you cannot open a new file that has been saved in the .DEF format you need to download the appropriate software. The manufacturer of .DEF files is N/A; .DEF files belong to the Developer Files category. After downloading the application from the list available on our website just run an unknown file, and as the default set the newly installed application supporting the .DEF files. Activities performed in the order described should solve the problems with all the files in the .DEF format.