[mvexel]

Not necessarily cool perhaps but a critical piece of OSM infrastructure is osm2pgsql[1].

Also important tools in OSM land are osmium[2] and imposm[3] but the latter I think is Go not C++.

[1] https://osm2pgsql.org/ [2] https://osmcode.org/osmium-tool/ [3] https://imposm.org/

[uneekname]

osm2pgsql makes it surprisingly easy to spin up your own tile server using OSM extracts

[mistrial9]

which recipe(s) do you like?