Homepage https://geojson.org
Using GeoJSON with Leaflet.js https://leafletjs.com/examples/geojson/
ArcGIS https://doc.arcgis.com/en/arcgis-online/reference/geojson.htm
Wikipedia Entry https://en.wikipedia.org/wiki/GeoJSON
http://switchfromshapefile.org/ goes over why shapefile bad and suggested alternatives
ESRI guide to work with JSON using ArcPy https://pro.arcgis.com/en/pro-app/tool-reference/conversion/json-to-features.htm