Help to improve the OpenStreetMap with StreetComplete!
This app finds incomplete and extendable data in your vicinity and displays it on a map as markers. Each of those is solvable by answering a simple question to complete the info on site.
The info you enter is then directly added to the OpenStreetMap in your name, without the need to use another editor.
An alternative for iOS is “Go Map!!”.
Unfortunately, it’s not available in my country :/