Nominatim (from the Latin, 'by name') is a tool to search OSM data by name and address (geocoding) and to generate synthetic addresses of OSM points (reverse geocoding). It can be found at nominatim.openstreetmap.org.
Nominatim is also used as one of the sources for the search box on the OpenStreetMap home page. Several companies provide hosted instances of Nominatim that you can query via an API, see section Alternatives below.
This page provides usage instructions. For details of how Nominatim works please see the Development Overview and there is a short FAQ. There is also a list of language mappings per country, some experimental address formats per country and a list of abbreviations.
The API documentation can be found at nominatim.org.
For the usage policy of nominatim.openstreetmap.org, please see Nominatim usage policy.
Nominatim is based around the postgresql import utility osm2pgsql using the alternative gazetteer output option. Indexing and search are performed using a combination of C, plpgsql and php. The source can be found here:
Full installation instructions can be found in on the nominatim.org website.
Bugs / Error reporting
When you report unexpected search results, please include the following in your bug report:
- the exact search term you were using
- links to the OSM objects you expect to find and, optionally, a link to the OSM object that was actually found
Alternatives / Third-party providers
For slightly larger requirements you may be able to use one the various third-party providers, though of course, you will need to agree to their terms of service.
If your requirements are even larger, you can install your own instance of Nominatim.
API Client Libraries
Note: before adding any libraries here you must make sure that it forces the user to set a custom user agent. It should also prominently point to the Nominatim usage policy.
Not endorsing the quality of these related projects, but consider using them as an alternative to writing your own. Please make sure you read the Nominatim usage policy before using this libraries. In particular make sure you respect the limit of 1 request/s.