Excel File Preview at Report and Attachment Viewer
Goal: Functional
Developer: Hengsin (talk)
Feature Ticket: IDEMPIERE-4801
Description: Add Excel file (xls, xlsx and csv) preview support to report and attachment viewer.
Usage
New popup menu after running of report with excel format output type:

Popup Menu
Select "Preview" to view contents of the excel file (using library from keikai.io):

view excel report
Example for attachment:

View Attached Excel File
Source: Wiki