Introduction: ST segment values are used to assess patients with suspected acute myocardial infarction. Given ST segment changes can be missed in busy clinical environments, researchers have proposed the ST Map as an alternative for depicting ST segment data. Given this approach has shown potential for use within routine clinical practice, we implemented a web based visualization system that could be used to further its acceptance. Methods: This ST Map software was developed using ActionScript 3.0 and the Adobe Flash IDE. The software parses ST values and draws two ST Maps that represent the horizontal and frontal planes respectively. ST values can be presented as vectors or as polygons. Conclusions: This tool can potentially be used as a decision support system where a user can input ST values and use the resulting graphic as an adjunct to assist a diagnosis. It can also be used as an educational tool for learning relationships between ST vectors and ischemic regions. Thirdly, the tool can be used as a web service by third party ECG applications and machines.