İdx extension is related to INDEX FİLE, Outlook , ReportBuilder or Foxpro. You can open idx extension with various softwares.

Idx extension is used with many different softwares. Idx file includes file list. After composing Hard disk files or database index, file creation and search process can be done fastly by the software. 
These following softwares compose index files to working folders:

Microsoft FoxPro,
Corel QuickFinder,
ESRI ArcView,
Outlook Express,

You don`t need to open idx files directly. If you wish you can delete these files. Then, when you open software again you will see the new index is occured. 

What to use idx

different softwares shown above

which page related to idx file

idx Related Searches

You can check related links about idx fileextension.