Last year I hiked the GR20 across Corsica, and afterwards I built a small non-commercial website around it: https://mongr20.com/en/

Everything is computed from the OpenStreetMap GR20 relation: the site states 182.4 km and +11,220 m of elevation gain, split into the 16 official stages. From that single OSM trace I generated:

• free GPX downloads for all 16 stages, in both directions (ODbL-credited): https://mongr20.com/en/gr20-gpx-tracks
• an interactive stage planner (pick 10, 12 or 16 days — it computes distance, elevation, water and food needs per day): https://mongr20.com/en/gr20-planner
• a refuge directory with positions and practical info.

The map tiles are OpenTopoMap/OSM. No ads, no tracking, no paywall — it is a thank-you project as much as anything. So: thank you to every mapper who has ever touched that red-and-white line across Corsica. The data quality on the GR20 relation is genuinely excellent, and this site simply would not exist without it.

If any mappers here have hiked the GR20 and spot something off (a refuge position, a water source), I would love to hear about it.