Eight years ago, I wrote a simple report viewer called RptView. Initially it was chargeable, then ad supported. One lesson I did learn is that neither of these models is a good way to make any money!
I’ve now updated it to use a more recent version of Crystal Reports and you can now download for free. However, it’s not supported unless you’re an existing customer of Pursuit Technology.
Main difference from the SAP viewer is that you can refresh the data in the report and that it includes a file browser to list all your reports.