They are using OSM as a major chunk of their source data (look at the copyright notice in the bottom left). Its just a nicer presentation layer In fact, I think it is by far the nicest OSM rendering that I’ve seen yet, given that the others don’t seem to be able to do contours without making everything else look worse.
I was wondering about nice online hiking maps for the rest of Europe and was intending to post a thread on this at some point, but now you’ve got there first, so here are the ones I’ve used in the recent past:
- For the UK, theres Bing Maps which has an Ordnance Survey option. This might not work outside of the UK or on mobile devices. There’s also Streetmap which has a fairly old-school interface but is otherwise functional.
- For France, there’s Géoportail. I don’t like the style of their maps much, but the actual content is quite high quality.
- For Spain, there’s Signa. The site seems a bit slow and awkward to use, for me. The maps are good at showing terrain in some detail, but aren’t nearly so good for paths.
- For Catalunya (and some bits of the Eastern Pyrenees, and Andorra) there’s IGCG. Signa covers the same area, but the style’s a bit different and the ICGC site is a bit faster for me.
- For Switzerland, there’s this, which doesn’t seem to have a nice short name. I’ve only used this for getting an idea of the terrain for skiing, so I don’t know much about the quality of path or track mapping here.
Some of these offer mobile and offline options, which I haven’t tried. I generally use paper maps when I’m offline, but I do sometime use OsmAnd (which is, obviously, for OSM on Android) and also openmtbmap to generate maps for my garmin GPS which are much better than the topo maps that Garmin have sold in the past.
Hope some of this might be useful.