Everything is stored locally in your browser. Public endpoints are intended for prototypes and light personal use.
Both map styles work without a map API key. Satellite uses Esri World Imagery with a place-name reference overlay; Road uses OpenStreetMap.
Gas-station locations come from OpenStreetMap along your route. Keep a HERE key only if you want HERE's station-level fuel prices; otherwise stations can still appear without a price.
Supported placeholders: {north}, {south}, {east}, {west}, {lat}, {lon}, {radiusMiles}, {apiKey}. Expected JSON can be an array or an object containing stations, results, or data.