Overview:
Discussion on the Openstreetmap service that has the most open map data that began in 2004.
Apps:
JOSM: Map editor
Comaps: Offline maps that's great for walking/hiking/cycling
Magic Earth: Great for driving
Related:
What’s wrong with Every Door or MapComplete? Also I remember an app that fed tasks from StreetComplete but can’t find it at the moment.
EDIT: That app I remembered is Go Map!! - click the "Map" button, then enable the "Quests" overlay. It looks similar to Street Complete and you can even design your own quests.
Not OP but I don't think there is anything wrong with them they just don't do things the same way.
And MapComplete doesn't have an ios app.
I use MapComplete all the time on my desktop PC and find it fantastic. I do have Every Door downloaded and have used it a handful of times, but to my knowledge it doesn't have the "tap here and answer a question" approach that StreetComplete does. If that is not true, I'd love to learn how to enable that!
See my original comment - it's Go Map that has the feature similar to Street Complete. Not quite as polished with those preview pictures and stuff, but it's more for OSM editors that know what they're doing anyways.
Ah, I do also have Go Map! on my phone. It is a pretty nice app in and of itself. I think the only thing it is missing compared to StreetComplete is the leaderboard.