Tendenci is the top ranked open source alternative to proprietary, closed source, or foreign government controlled open source AMS systems. Software screen shots of a mature and highly focused AMS System for your NGO or Association are here and from a global perspective.
If in the global market for an AMS for your NGO or Association, be sure to check out the AMS Screenshots. And of course kick the tires on the demo site at https://demo.tendenci.com/