GeoCommons – A public community archive and set of tools to access, visualize and analyze data with compelling map visualizations.
Kepler - an open source geospatial analysis tool for large-scale data sets.
Leaflet JS – A lightweight JavaScript library for making tile-based interactive maps for desktop and mobile browsers.
Mapbox – A web platform for hosting custom designed map tiles and a set of open source tools to produce them.
Modest Maps – a small, extensible, and free library for designers and developers who want to use interactive maps in their own projects.
OpenLayers– Javascript mapping library.
CartoDB– online tool for visualizing data on a map (the open source, installable version of CartoDB can be found here).
WorldMap (ArcGIS) - low barrier open source platform to explore, visualize, edit, collaborate with, and publish geospatial information.
gmaps.js – a light-weight Google Maps API.
Ushahidi – online platform to collect and display information geospatially.
Timemap.js – Javascript library to help use online maps, including Google, OpenLayers, and Bing, with a SIMILE timeline. The library allows you to load one or more datasets in JSON, KML, or GeoRSS onto both a map and a timeline simultaneously.
Bootleaf – Template for building simple and elegant web mapping applications with Bootstrap 3 and Leaflet
Leaflet Time-Slider – The Leaflet Time-Slider enables you to dynamically add and remove Markers on a map by using a JQuery UI slider.
odyssey.js – a javascript library that enables the development of story-maps (combination of linear narratives with maps and map interactions). Currently in early development.
Story Maps (ESRI) Story maps combine interactive maps and multimedia content into elegant user experiences. They make it easy for you to harness the power of maps to tell your stories.
StoryMaps JS (KnightLab Foundation) – StoryMapJS is a free tool to help you tell stories on the web that highlight the locations of a series of events.
Neatline – geotemporal exhibit-builder that allows you to create beautiful, complex maps, image annotations, and narrative sequences from Omeka collections of archives and artifacts, and to connect your maps and narratives with timelines that are more-than-usually sensitive to ambiguity and nuance.
Flourish Maps - a data visualization tool by Canva for creating visual components.
Datawrapper - lets you show your data as beautiful charts, maps or tables with a few clicks.
Leaflet Tile Server/Service Browser (also provides the leaflet specific code for specific tile sets) - https://leaflet-extras.github.io/leaflet-providers
Thunderforrest (pay service, but has a generous free tier) - https://www.thunderforest.com/
Ancient World Mapping Center Tiles - http://awmc.unc.edu/wordpress/tiles/
Stamen - http://maps.stamen.com/
Open Streetmap Raster Tile Providers - https://wiki.openstreetmap.org/wiki/Raster_tile_providers
Map Tiler Server (host and run your own map tile server) - https://www.maptiler.com/server/
Open Map Tiles (free map tiles to be used with Map Tiler Server) - https://openmaptiles.org/
Mapbox – A web platform for hosting custom designed map tiles and a set of open source tools to produce them.
Mapbox Interactive Storytelling Templates - https://labs.mapbox.com/education/impact-tools/interactive-storytelling/