Rainfall monitoring conducted by BMKG, is the capital as the basis of this research which aims to create a web-based landslide early warning system in the City of Pagar Alam, by recording the rainfall that occurs as an anticipatory material for landslides in the Pagar Alam area. In order to make this research work as expected as an early warning system that can be accessed online, a research methodology and in-depth analysis are used. With the Rapid Application Development (RAD) system development method, the design uses flowchart and Unified Modeling Language (UML), with the PHP programming language and MySQLi database. The result of this research is a web-based early disaster landslide early warning system in the City of Pagar Alam area which is a mountainous area, by utilizing the classification of very light, mild, moderate, heavy and very heavy rainfall.