Flow maps are cartographic visualizations to show the movement of objects, people, or other living things from one location to another. Lines, usually symbolized with an arrow to indicate the direction. Color coding or line width can also then be used to indicate the volume of objects that are moving from one location to another. Airline traffic, animal migration, commuters, and import/exports are all common types of geographic data that are typically shown on a flow map (more: Overview of Flow Mapping).
Ilya Boyandin has developed an easy-to-use online tool called Flowmap.blue that takes location data stored in Google Sheets to visualize interactive flow maps. Built using flowmap.gl, deck.gl, mapbox, d3, blueprint, CARTOColors, Flowmap.blue is a browser-based tool that lets users visualize and animate the movement of geographic data between locations.
User can quickly set up their own custom flow maps by copying the template spreadsheet and adding in their own location data. The site also hosts plenty of examples that showcase how flowmap.blue was used to map out commuter trips, bicycle rides and sharing trips, human migration, animal migration patterns, and modeling a sewer system.
Flow maps can easily be shared or embedded into websites like the example below.