Leaflet is a modern, lightweight open-source JavaScript library for mobile-friendly interactive maps. It is developed by Vladimir Agafonkin of CloudMade with a team of dedicated contributors. Weighing just about 22 KB of gzipped JS code, it still has all the features most developers ever need for online maps, while providing a fast, pleasant user experience.

It is built from the ground up to work efficiently and smoothly on both desktop and mobile platforms like iOS and Android, taking advantage of HTML5 and CSS3 on modern browsers. The focus is on usability, performance, small size, A-grade browser support and an easy-to-use API with convention over configuration. The OOP-based code of the library is designed to be modular, extensible and very easy to understand.