I’ve built a site to create an open geocoding dataset over at

The premise I worked with is to change the way geocoders work. Today, a geocoder uses some chunk of import code to import a large dataset from one format in to another. Then the geocoder itself (which is a large piece of software) takes a string from the user like “london” and uses it’s imported dataset to eventually give you a bounding box. The client uses this bounding box to zoom and pan a map to the correct place.

What if you threw all that away and just linked the string “london” to a bounding box? Thus opengeocoder.

In previews the number one thing asked for was synonym support. That is, “AK” should spit out the same box as “Alaska” without having to add both strings and two bounding boxes. So, you can do that. There is an API which spits out JSON so you can hook your map project up to it.

OpenGeocoder starts with a blank database. Any geocodes that fail are saved so that anybody can fix them. Dumps of the data are available.

There is much to add. Behind the scenes any data changes are wikified but not all of that functionality is exposed. It lacks the ability to point out which strings are not geocodable (things like “a”) and much more. But it’s a decent start at what a modern, crowd-sourced, geocoder might look like.

10 Responses to OpenGeocoder

  1. pythoncharming February 22, 2012 at 7:08 am #

    How are you supporting containment of bounding boxes, like ‘london, uk’ type queries?

    • stevecoast February 22, 2012 at 7:26 am #

      it’s just another string as far as opengeocoder is concerned

  2. Ilya Zverev February 22, 2012 at 4:34 pm #

    How do I enable OSM layer in that app?

    • stevecoast February 23, 2012 at 1:25 am #

      you can’t, since deriving from OSM would imply the data should be CC and not PD

  3. Glen Barnes (@barnaclebarnes) February 23, 2012 at 1:19 am #

    So what happens when you have conflicts between the different cited named London – Is there any sort of ordering or hinting? Who ‘wins’ in this situation?

    • stevecoast February 23, 2012 at 1:24 am #

      Try things like “london” on any map large map site. Most of them just make a decision for you that you mean the london in the uk. This is unlike normal web search where you are presented with multiple options.

  4. David Masclet March 15, 2012 at 6:11 pm #


    i have started an opensource geocoder (and some other webservices) five years ago called gisgraphy. do you think it can help? tell me if i can contribute in anyway. i think the relevance is pretty good.

    you can try it at
    main site at

    David masclet

  5. Stefano June 12, 2012 at 12:19 am #

    What about toponym translation?
    Two bounding boxes for French and English for example?


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