MapIt is a service that maps geographical points to administrative areas. It’s useful for anyone who has the co-ordinates of a particular point, and needs to find out what regions it lies within. It’s also great for looking up the shapes of all those boundaries.

This particular instance of MapIt contains approximate boundaries for postcodes, postcode sectors, postcode districts and postcode areas, based on the Voronoi diagram of postcode centroids from ONSPD. You can also read more about the project to make these boundaries.

Please don't scrape this data in bulk: there's no point, since you can can download it all in one go instead. Extracting the data by scraping uses up a lot of server resources. If for some reason that's not good enough for you, please email me.

You can download from GitHub the the source for the core Django MapIt application, or the source code specific to this instance (i.e. everything to do with approximate postcode boundaries).

MapIt API Documentation

The documentation below is for developers who want to use MapIt as a web service, describing its REST API. If that’s all Greek to you, please see our page for non-developers.

lookup by postcode

URL:
/postcode/[postcode]
Returns:

Information on a particular postcode, including its location in WGS84 latitude/longitude, and the areas it is contained within.

Optional query parameters:

generation, to return results from a previous generation.

Example:

If your postcode was SW1A 1AA you would load /postcode/SW1A1AA

By default the response is in JSON, if you want a human readable page then append ‘.html’ to the url /postcode/SW1A1AA.html

lookup by partial postcode

URL:
/postcode/partial/[partial postcode]
Returns:

Geographical details for the centroid of the partial postcode specified.

Example:

lookup by point

URL:
  • /point/[SRID]/[x],[y]
  • /point/[SRID]/[x],[y]/box
Parameters:

SRID is a unique number referring to a particular co-ordinate system; the ones you probably are interested in are 27700 for British National Grid, 4326 for WGS84 lon/lat, and 29902 for the Irish National Grid.

x and y are the co-ordinates of the point in the co-ordinate system; note that x,y means longitude,latitude.

Optional query parameters:
  • type, to restrict results to a particular area type or types (multiple types separated by commas);
  • generation, to return results for a previous generation.
  • min_generation, to return results since that generation.
Returns:

A hash of the areas that the point is contained within. If the /box version is used, only the area bounding boxes are considered.

Example:
Example of areas containing (400000,300000).

lookupnearest postcode

URL:
/nearest/[SRID]/[x],[y]
Parameters:
Same as for by point.
Returns:
The postcode closest to the particular point.
Example
Example of postcode nearest to (400000,300000).

lookup by area

URL:
  • /area/[area ID or ONS code]
  • /area/[area ID]/example_postcode
  • /area/[area ID]/geometry
  • /area/[area ID].[kml or geojson or wkt]
  • /area/[SRID]/[area ID].[kml or json or wkt]
Optional query parameters:
simplify_tolerance, a floating point parameter to simplify the polygons returned.
Returns:
Information on a particular area, including name, type, parent, and any associated codes (see below for details). The code lookups redirect to the area URI. example_postcode returns a random postcode within the area specified. geometry returns centroid, extent and area of the area.
Examples:

lookup multiple areas

URL:
  • /areas/[area IDs]
  • /areas/[area IDs]/geometry
  • /areas/[type(s)]
  • /areas/[name prefix]
Parameters:
Separate multiple parameters with commas. Name prefix means it will return any area that starts with the string given. The area types in use are APA (Approximate postcode areas), APD (Approximate postcode districts), APS (Approximate postcode sectors) and APU Approximate postcode units).
Optional query parameters:
  • generation, to return areas in that generation (type and name lookups only).
  • min_generation, to return areas since that generation (type and name lookups only).
  • type, to restrict results to a type or types (multiple separated by commas; name lookup only).
Returns:

Information on multiple areas that match the parameters provided, as a dictionary indexed by area ID. The geometry argument lets you fetch multiple single area geometry results at once.

Examples:

lookup by code

URL:
  • /code/[code type]/[code]
Parameters:
code type and a code should uniquely identify an area. (MapIt uses code types and codes to associate external identifiers with areas.) The only code type in use is: uk-pc (A full or partial UK postcode)
Returns:

This returns an HTTP 302 Found redirect to the corresponding /area/[area ID] page. Any format extension (.html or .json) will be preserved in the URL that's redirected to.

Examples:

Generations

URL:
/generations
Returns:
A list of all generations in this installation of MapIt.
Note that only generations from 12 upwards actually exist, apart from some council names in generation 10 in order for FixMyStreet to show expired councils on its All Reports page.
Example
List of generations

General information

Format

All calls return JSON, you can generally get an HTML representation by sticking .html on the end.

Whenever an area is returned from MapIt, it is as a dictionary with the following keys: id, name, country, type, parent_area, generation_low, generation_high, codes.

Historical areas
By default, calls will return active areas; for some calls you may specify a previous generation to look up instead.

About MapIt

MapIt was written back in 2003 as a postcode lookup to power the original mySociety sites such as WriteToThem. Over time it gained features such as point lookup (for FixMyStreet), and when Ordnance Survey data became freely available in 2010, it was rewritten and made public for the whole UK. Versions have appeared in other countries, such as Norway, and in 2012 we released a global version based on OpenStreetMap data.

Usage & Licence

To maintain quality of service for our own websites, as well as our API users, this service is rate limited to an average of 1 call per second in a rolling 3 minute period.

If you use this service, we ask that you attribute MapIt at the point of use on sites or apps. Attribution should use the text “Powered by MapIt”, with a link back to this page.