Background Severe hyperbilirubinemia is more frequent in low- and middle-income countries such as Indonesia than in high-income countries. One of the contributing factors might be the lack of adherence to existing guidelines on the diagnosis and treatment of hyperbilirubinemia. We developed a new national guideline for hyperbilirubinemia management in Indonesia. To help healthcare workers use this guideline, a web-based decision support tool application may improve both the adherence to the guideline and the care for infants with hyperbilirubinemia. Methods We developed a web-based application (BiliNorm) to be used on a smartphone that displays the bilirubin level of the patient on the nomogram and advises about the treatment that should be started. Healthcare workers of two teaching hospitals in East Java, Indonesia, were trained on the use of BiliNorm. At 6 months after the introduction, a questionnaire was sent to those who worked with the application enquiring about their experiences. An observational study was conducted in two time epochs. A chart review of infants with hyperbilirubinemia in the two hospitals was sent. The appropriateness of hyperbilirubinemia management during a 6-month period before BiliNorm introduction was compared to that during a 7-month period after its introduction. Results A total of 43 participants filled in the questionnaire, the majority (72%) of them indicated that BiliNorm was well received and easy to use. Moreover, 84% indicated that BiliNorm was helpful for the decision to start phototherapy. Chart review of 255 infants before BiliNorm introduction and that of 181 infants after its introduction indicated that significantly more infants had received treatment according to the guideline (38% vs 51%, p = 0.006). Few infants received phototherapy, but bilirubin level was not measured (14% vs 7%, p = 0.024). There was no difference in the proportion of infants who were over- and under-treated (34% vs 32% and 14% vs 10%, respectively). Conclusions The web-based decision tool BiliNorm appears to be a valuable application. It is easy to use for healthcare workers and helps them adhere to the guideline. It improves the care for infants with hyperbilirubinemia and may help reduce the incidence of severe hyperbilirubinemia in Indonesia.