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.
I have found convenience store within 5 minutes walking distance from my house thanks to StreetComplete. I had solved most of the tasks nearby, so I took a small detour on my way home and found this shop there that I had no idea existed. At that stage I was living in the area for years.