Nominatim - Behind the scenes

Most mappers and users of OSM are -knowingly or not- users of Nominatim. The software behind the search box on is a powerful search engine that allows to do free-form searches over almost anything in OSM that has a name. It is able to keep up-to-date with the latest edits and also supports reverse geocoding.

This talk takes a look inside OSM's main geocoder. It explains how the raw OSM data is processed into a huge address database and how a search query is turned into the right answer (or not on some occasions). The focus is less on the technical details but more on the general principles, clearing up some of the mysteries and misconceptions around Nominatim, helping the interested mapper to better understand how their carefully mapped areas are turned into something that can be found by others.

at FOSSGIS 2013 Rapperswil (German)

at State of the Map 2013 Birmingham (English)