Flowmap.gl
Flowmap.gl is a library for visualizing movement of people (e.g. migration) or objects between geographic locations:
It provides a GPU-accelerated flow layer for applications that need to render many curved origin-destination links interactively. I originally developed it while working on mobility analytics, where dense movement datasets quickly become too slow or visually cluttered for traditional SVG or canvas rendering.
The library uses WebGL for rendering. Hence, it can handle relatively large numbers of flows with a good rendering performance:
Morning and evening peaks: