AccessMod is a desktop tool developed by the World Health Organization (WHO) to help countries assess the geographic accessibility of their health system. The first release of the tool was 18 years ago, and it has been widely used since by various groups within and outside WHO to support better strategic investment decisions and the planning processes of policies supporting Universal Health Coverage (UHC). Bluesquare is developing an online version of the tool at the request of WHO. In the session, Bluesquare will share its experience in implementing a scientific tool as a scalable and user-friendly web application.