Leaflet is an open‑source JavaScript library for building mobile‑friendly, interactive web maps.

Quick Scoop

  • It lets you add maps to websites and web apps, then place markers, popups, and shapes on top of those maps.
  • It is designed to be lightweight (around 42 KB of core JS) but still cover most mapping needs for typical web projects.
  • You can load data (for example GeoJSON), style it, and make it interactive with clicks, hovers, and custom controls.
  • It works well on both desktop and mobile browsers and is extendable via many community plugins (for heatmaps, clustering, etc.).

Where Leaflet Shows Up

Common uses include:

  1. Embedding store‑locator maps on business sites.
  1. Visualizing geographic data (like routes, regions, or sensor locations) in dashboards.
  1. Creating custom web GIS tools without needing deep GIS background.

In simple terms: Leaflet is the “interactive map engine” many sites use behind the scenes to show and interact with maps in the browser.

TL;DR: If you’re asking “what is Leaflet?” in 2026, it’s still one of the most popular JavaScript libraries for fast, simple, interactive web maps on both desktop and mobile.

Information gathered from public forums or data available on the internet and portrayed here.