I've read an API documentation for Leaflet on its site, but I can't realize: what is a default projection to view maps? It was written about spherical and elliptical Mercator and Equirectangular - so which of this three? Or does it depend on tile server I use, or it doesn't depend since leaflet reproject tiles instantly on-the-fly before adding on the screen?
Actually i can't understand what projection i need to save geoJSON files in QGIS. To display correctly on the leaflet map, json coords should be lat-long, not x-y. But if i try to save it in Equirectangular - coords will be x-y..?