CartoDB is an online tool that streamlines the creation of GIS based visualizations. It’s easy to use GUI allows users to rapidly upload datasets containing geographic information, and to plot the data onto maps.  Built on industry proven open source software, like PostGIS, PostgreSQL, and JavaScript, CartoDB allows users to write powerful code (if desired), and to produce reliable and content-rich visualizations.

CartoDB offers many of its services for free, however access to their API, and some more advanced features requires a subscription and payments.

An image of a map  created using CartoDB shown below:

By Steven Vance from Chicago, United States – Parking Pay Boxes in Chicago – map screenshot, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=43114946