Understanding OpenFreeMap and Leaflet Integration

OpenFreeMap is a popular open-source map tile hosting service that provides free, high-quality vector map tiles. However, because OpenFreeMap serves modern vector tiles (style JSON files powered by MapLibre) rather than traditional raster image tiles, integrating it into Leaflet can feel confusing at first.

Leaflet's default function, addTiles(), expects standard raster tile URLs (formatted as XYZ image templates like https://.../{z}/{x}/{y}.png). Since OpenFreeMap is not pre-listed in Leaflet's addProviderTiles() helper, you need to either render its vector styles using a MapLibre GL plugin or point to supported tile templates.

Here is how to easily render OpenFreeMap base tiles in both R Leaflet and JavaScript Leaflet.

Method 1: R Leaflet using leaflet.extras2 (Recommended)

The cleanest way to display vector styles from OpenFreeMap in R's leaflet library is to use the leaflet.extras2 package, which adds support for MapLibre GL style JSON files.

Step-by-Step R Code: