Atlas
GPS workout heatmap viewer
Upload your GPX workout files and Atlas turns them into a personal heatmap: streets and trails you've run once show up in blue, the ones you cover all the time glow orange/red, with a smooth gradient in between based on real, distance-matched crossings (not just raw GPS points). Click any activity in the list to highlight that single route on the map. Everything runs client-side, tracks stay in your browser's local storage, and you can export/re-import your data as JSON at any time.