摘要:Application Programming Interfaces (APIs) are software tools that help different programs work together. APIs can improve an organization's presence on the Web with tools that integrate various useful, popular programs. This study aimed to identify appropriate web-based APIs used by the most popular public library websites for presentation on Iranian public libraries’ websites. For this purpose, we conducted this study in two stages: In stage one, Web APIs were identified by reviewing the websites of the top public libraries in the world. Then, in stage two, using the obtained results, important Web APIs were selected utilizing experts' opinions (the heuristic method). In stage one, the 30 Web APIs in two categories were identified: 10 public Web APIs and 20 private Web APIs. Then, in stage two, 7 public APIs and 17 private Web APIs for these websites were selected, based on expert analysis. The results of this study can be used to improve the design of public library websites and enhance the communication of such websites' presence on the Web.