The City University of New York (CUNY) and Ithaka S+R developed a supportive credit mobility system to overcome barriers in the student transfer process. Launched in May 2020, the City University of New York (CUNY) Transfer Explorer (CUNY T-Rex) exposes course and credit-for-prior-learning (CPL) transfer rules as well as general education and major requirements for CUNY's 20 undergraduate colleges through a centralized website. Through CUNY T-Rex, users have access to accurate, real-time data on CUNY's 1.6 million transfer rules and can explore how courses and CPL experiences transfer and apply to programs of study. This report analyzes the enabling conditions and factors that led to CUNY T-Rex's successful development and growth. Understanding the context around the implementation of a successful resource, operating in a large system of higher education institutions, provides valuable insights into the essential elements of a credit mobility technology solution.