Two Giants of Web Mapping
When building interactive maps for the web, two libraries dominate the conversation: Leaflet and Mapbox GL JS. Both are powerful and widely used, but they take fundamentally different approaches to rendering and interaction. Choosing the right one depends on your project requirements, technical constraints, and budget.
At a Glance
| Feature | Leaflet | Mapbox GL JS |
|---|---|---|
| Rendering | DOM/SVG/Canvas (raster tiles) | WebGL (vector tiles) |
| Bundle size | ~40 KB gzipped | ~250+ KB gzipped |
| 3D support | Limited (plugins) | Built-in (pitch & bearing) |
| License | BSD-2-Clause (fully open) | Proprietary (v2+) |
| Learning curve | Gentle | Moderate |
| Plugin ecosystem | Very large | Growing |
| Data-driven styling | Manual/plugin | Native (style spec) |
| Map rotation/tilt | No (without plugin) | Yes |
Leaflet: The Lightweight Champion
Leaflet was created by Volodymyr Agafonkin and released in 2011. It remains one of the most popular open-source JavaScript libraries ever made — and for good reason.
Strengths
- Tiny footprint: At around 40 KB gzipped, Leaflet loads fast even on slow connections.
- Simplicity: Its API is clean and intuitive. You can have a working map with a tile layer in under 10 lines of code.
- Massive plugin ecosystem: Hundreds of community plugins cover routing, clustering, heatmaps, geocoding, and much more.
- Fully open source: BSD-2-Clause license — use it freely in any project, commercial or otherwise, with no usage limits.
- Works everywhere: Excellent support for older browsers; no WebGL required.
Limitations
- Raster-tile rendering means styles are baked into tile images — you can't dynamically restyle map features client-side.
- No native 3D, globe projection, or map rotation.
- Performance can degrade with very large GeoJSON datasets rendered directly on the map.
Mapbox GL JS: The Feature-Rich Powerhouse
Mapbox GL JS uses WebGL to render vector tiles, meaning every road, building, and label is rendered as geometry on the GPU — not as a pre-drawn image.
Strengths
- Vector tile rendering: Smooth zoom at any level, crisp on high-DPI displays, and dynamically styleable.
- Data-driven styling: Style map features (color, size, opacity) based on their data properties using the Mapbox Style Specification.
- 3D terrain & buildings: Native support for pitched views, 3D extrusions, and terrain elevation.
- High performance: GPU rendering handles large datasets and complex styles efficiently.
- Globe projection: Newer versions support globe-level zoom.
Limitations
- License change (v2+): From version 2 onward, Mapbox GL JS is proprietary and requires a Mapbox account and API token. Heavy usage incurs costs. The last open-source version is v1.x.
- Larger bundle size increases initial page load.
- Requires a browser with WebGL support (though this is nearly universal today).
- The style specification has a steeper learning curve than Leaflet's imperative API.
The Open-Source Alternative: MapLibre GL JS
If you want Mapbox GL JS's WebGL capabilities without the licensing concerns, consider MapLibre GL JS — a community-maintained fork of Mapbox GL JS v1 that remains fully open source under BSD license. It's API-compatible with older Mapbox GL JS code and is actively developed.
When to Choose Leaflet
- You need a simple, fast, lightweight map with standard raster tiles.
- Your project requires broad browser compatibility or operates in low-bandwidth environments.
- You're building a quick prototype or don't need 3D/rotation features.
- Open-source licensing with no usage costs is a hard requirement.
When to Choose Mapbox GL JS (or MapLibre)
- You need smooth vector tile rendering and dynamic, data-driven map styles.
- Your application requires 3D terrain, building extrusions, or map rotation/tilt.
- You're building a data-rich application with complex visual encoding.
- You want a professional, polished basemap with fine-grained style control.
Bottom Line
There is no universal winner. Leaflet excels for simplicity, speed, and open-source freedom. Mapbox GL JS (or MapLibre GL JS) excels for rich, interactive, data-driven maps. Many developers start with Leaflet and migrate to a WebGL renderer when they need more power — and that's a perfectly valid path.