WellCareTracker™ has its roots in a stand-alone software program called ECELSTRAK, which was first developed in 1995 by Stuart T. Weinberg, MD with the support of the PA Chapter of the American Academy of Pediatrics (PA AAP), particularly Drs. Jerry and Susan Aronson and then PA AAP Executive Director Suzanne Yunghans. The software was written using the Knowledgeman database management system from Micro Data Base Systems, Inc.

The initial purpose of the software was to facilitate centralized data collection and analysis by PA AAP's Early Childhood Education Linkage System (ECELS) program, the mission of which is to improve the quality of early childhood education and school age child care programs. ECELSTRAK focused specifically on child health data related to preventive health services, including health screenings, assessments, and immunizations. The software applied the latest immunization recommendations from the CDC and preventive health care recommendations (Periodicity Schedule) from the American Academy of Pediatrics, determining if a child was due, overdue, or up-to-date for each of the services/immunizations.

By early 1997, over 30 child care sites expressed an interest in field testing a newer version of ECELSTRAK that could be run at each site. From a letter sent to these sites, "We know that manual checking of records is tedious. We think that child care providers will prefer entering the data into a computer so the computer can check the records at any point in time, scanning the files and generating a printout of who needs to get updated for specific services. Having the computer generate an individual report for each child as well as a summary for the whole facility of the services needed for each child should make the job of notifying parents and the child's doctor about missing data easier. ECELSTRAK, the software the PA AAP is developing can do this work for you." ECELSTRAK not only helped child care programs keep their children healthy and up-to-date in an easier (digitized) way but also helped them meet PA state regulatory requirements.

In 2002, ECELSTRAK was ported to a web-based application and renamed WellCareTracker™ (WCT). By 2004, WCT was accessed by 346 distinct users. Although WCT was originally intended for use by Pennsylvania child care centers, inquiries outside of PA resulted in users from Connecticut, Illinois, Louisiana, Texas, Utah and Washington.

WCT continues to be used by child care centers across the country and has been recently updated to accommodate COVID vaccine information.