Bit focused on eastern Europe, but has a hiking mode with very good coverage of the official routes (not only in eastern Europe ;)). And everything is free, including offline maps. Terrific value for casual trips.

https://play.google.com/store/apps/details?id=com.bergfex.to...

This one is not free (there is a free tier though) but seems to have more details in some areas, so the pro tier may be worth it if you hike a lot.