The analyser.openstreetmap.fr service is a relation analyse tool in real time. Given a relation id, it tests for validation of multipolygons of any kind, admin boundaries (and also linear relations to some extend). It is hosted at French association servers.
You can use permalinks of the form: http://analyser.openstreetmap.fr/cgi-bin/index.py?relation=123456.
You can use talk page for questions.
The result is a map, with the relation displayed over it. Tags, nodes where the problem is are displayed.
- A yellow marker is displayed for an opening in the relation
- A green Marker for self intersection
A direct link to JOSM is given to repair the relation where it has a problem.
A copy of this tool, but faster can be found here : http://api.openstreetmap.fr/analyse/
This version doesn't use data from the main OSM database, but from a copy. This copy can be from 1 to 5 minutes late. But it might be faster. Some relations can fail analysing with the previous instance and succeed with this one (due to timeout).
Code is here https://github.com/osm-fr/relation-analyser