QGIS is a free, open-source GIS platform for desktop that offers many common GIS functionalities provided by core features and plugins. QGIS also connects with numerous additional cloud-based tools, such as Mapbox and Carto. | Overview
Simply Map is a web-based mapping application with access to thousands of demographic, business, and marketing data variables that can be used to develop interactive thematic maps and export high-resolution images to word processing or presentation software.
Leaflet is a Java Script library used to create mobile-friendly interactive maps. You must install map libraries on your own server. Alternately, display Leaflet tiles via a plug-in within Wordpress | Overview