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geoJson or vector style editor? For the former, QGIS is a good bet. For the latter, maputnik.

GeoJSON. Was hoping there was something lighter than QGIS as I just want to create a collection of markers, no unique shapes, point clouds, etc.

Maybe check out geojson.io then. It may be too lightweight but perhaps it meets most of your functionality (assuming you will have a web connection).