I once found a great but simple webpage that has a drop down with several text-based GIS formats such as GeoJSON and WKT, and a text box to copy/paste your data. The feature is then drawn on a world map. You can continue to add shapes on the same map.
I've lost this page, and I can't find it. It was super-useful, but I forgot to bookmark it.
So, does anyone know the page, or any page where I can paste WKT and GeoJSON to see them displayed on a map?