We describe a new tool that automatically identifies impact of customization changes, i.e., how changes affect software behavior. As opposed to existing static analysis tools that aim at aiding programmers or improve performance, our tool is designed for end-users without prior knowledge in programming. We utilize state-of-the-art static analysis algorithms for the programs within an Enterprise Resource Planning system (ERP). Key challenges in analyzing real world ERP programs are their significant size and the interdependency between programs. In particular, we describe and compare three customization change impact analyses for real-world programs, and a balancing algorithm built upon the three independent analyses. This paper presents Panaya Impact Analysis (Panaya IA), a web on-demand tool, providing ERP professionals a clear view of the impact of a customization change on the system. In addition we report empirical results of Panaya IA when used by end-users on an ERP system of tens of millions LOCs.