So, imports. When I was working at Maps.Me, many companies asked if we can put them on the map. So I made another thing.
OSM Conflator takes a data source and carefully merges it with OSM data, with a way to update it later.
https://wiki.openstreetmap.org/wiki/OSM_Conflator
While it can take a plain JSON with tags, it is most powerful with profiles: Python scripts that control the behaviour.
It can export a preview GeoJSON and has other ways of adhering to the guidelines. Alas, few people had enough skill to use it.
Having a GeoJSON to preview an import is good, but how to suggest amendments?
That's why I made CF Audit: an interactive website to go through changes one by one, cross-reference them, and fix anything wrong.
Those fixes are kept for consequent imports with OSM Conflator, so less work next time.
http://audit.osmz.ru/
I know RocketData iterated on it for their operations, and there's a new IFS fork by @sfkeller team: https://cfauditgui.geoh.infs.ch/