Leaflet

Leaflet is the leading open-source JavaScript library for mobile-friendly interactive maps. Weighing in at just about 42 KB of JS, it has all the mapping features most developers ever need. It was designed with simplicity, performance, and usability as its core goals, making it a preferred choice for developers over more heavyweight proprietary alternatives.

Originally created by Vladimir Agafonkin, the library has since grown into a massive community-led project with hundreds of contributors worldwide. Because it is open-source software under the BSD-2-Clause License, it does not have a traditional corporate manufacturing origin, but rather a digital one maintained through collaborative coding platforms. It is extensively used by major organizations including GitHub, Pinterest, and The New York Times to power their spatial data visualizations.