Center Node is a JOSM plugin to create or replace the selection with the center node (at the topological average of the selection).
In JOSM, go to Menu Bar > Edit > Preferences > Plugins and search for "centernode".
Create an issue on github or contact me on osm.
Written in Kotlin using Florian Schäfer's excellent Gradle plugin.
Found a bug and know the cause?
Made an improvement?
I'm open to any pull request or suggestion.