Leaflet, a lightweight and open-source mapping library that leverages OpenStreetMap, offers a free alternative to Google Maps and MapBox, and can be used in React applications through React Leaflet. This article provides a comprehensive guide on setting up a React app with React Leaflet to render maps, customize markers, and manage data display, both locally and remotely using SWR for data fetching. The tutorial includes detailed code examples for displaying skateboard park locations and crime data on maps, along with instructions for handling popups and customizing marker icons. Emphasizing Leaflet's ease of use and light footprint, the article positions it as a viable choice for developers seeking a free mapping solution, while also highlighting performance considerations when dealing with a large number of markers.