Leaflet
Lightweight JavaScript library (42KB) for building interactive web maps with tile layers, markers, popups, GeoJSON overlays, and a rich plugin ecosystem.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Client-side library with no network calls of its own; ensure tile API keys are not exposed in client-side code for private or rate-limited tile providers; sanitize popup HTML content to prevent XSS
⚡ Reliability
Best When
You need a lightweight, well-documented library to add an interactive 2D web map with minimal bundle size and broad browser compatibility.
Avoid When
You need 3D terrain, complex vector tile styling, or WebGL-accelerated rendering of millions of features.
Use Cases
- • Embedding an interactive tile-based map in a web application with minimal JavaScript
- • Displaying GeoJSON feature collections as interactive overlays with click/hover handlers
- • Adding custom markers, popups, and tooltips to geographic data visualizations
- • Building mobile-friendly map interfaces that work across all modern browsers
- • Extending functionality through the plugin ecosystem (clustering, heatmaps, drawing tools)
Not For
- • Server-side map rendering or static image tile generation (use Mapnik or MapLibre GL Native)
- • 3D globe visualization or terrain rendering (use Cesium or MapLibre GL JS with terrain tiles)
- • Large-scale vector tile rendering with complex styling (use MapLibre GL JS instead)
Interface
Authentication
Client-side JavaScript library — no authentication required. Tile providers (OpenStreetMap, Mapbox, etc.) may require separate API keys for their tile endpoints.
Pricing
BSD 2-Clause license. Leaflet itself is completely free. Costs may arise from the tile provider you choose (e.g., Mapbox charges for tile requests beyond their free tier).
Agent Metadata
Known Gotchas
- ⚠ Coordinate order is [latitude, longitude] for L.latLng and most Leaflet APIs, but GeoJSON uses [longitude, latitude] — mixing these is the single most common agent mistake
- ⚠ The map container div must have an explicit CSS height set or the map renders as 0px tall with no error
- ⚠ Tile provider attribution is legally required by most tile services (OSM, Stadia, etc.) — omitting it violates usage terms
- ⚠ Leaflet does not support WebGL or vector tiles natively — agents expecting MapboxGL-style features must use a plugin like Leaflet.VectorGrid
- ⚠ Adding thousands of markers directly without clustering causes severe DOM performance degradation — agents generating marker-heavy maps must use Leaflet.markercluster plugin
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for Leaflet.
Scores are editorial opinions as of 2026-03-06.