UDF files are executable files that are mainly associated with Microsoft Excel, according to FILExt, an online database of file extensions. UDF stand for "User-Defined File," which means that the file is a user-defined script that can be written or recorded. You can create, open and edit UDF files with Microsoft Excel.
Right-click on the UDF file.
Click on "Open with."
Select the "Choose Default Program" option.
Select Microsoft Excel.
Click on "Browse" only if Microsoft Excel is not on the list. Then, search for it and click on "Open."
Click on "OK." Your UDF file will open.
Click on "File."
Click on "Save as."
Select the file extension you wish to convert the UDF file to.
Click on "Save." Your UDF has been edited.