Building a GPX Editor with TypeScript and Leaflet

Cyclists and outdoor enthusiasts accumulate GPX files from GPS devices and phone apps, but editing these tracks typically required desktop software. Modern browser APIs and mapping libraries make it possible to build a fully functional GPX editor that runs entirely client-side.

The editor supports three essential workflows: loading existing GPX files, modifying waypoints, and exporting clean tracks. The Douglas-Peucker algorithm handles route simplification by removing redundant points while preserving overall shape — critical for reducing file size without losing meaningful route data.

Elevation profiles are rendered using Chart.js, giving immediate visual feedback on terrain difficulty. Users can trim start and end points, useful for removing the drive to the trailhead from a ride recording.

Leaflet was chosen over Mapbox GL for its smaller bundle size and permissive BSD license. TypeScript provides type safety across the coordinate manipulation logic, which is where most bugs surface in geospatial applications. Vite enables fast development iteration with instant hot module replacement.