MapIt for non-developers

What is MapIt?

There's one quick and easy way to understand MapIt if you’re someone who doesn’t code: take a look at one of the sites that uses it, like our own WriteToThem.

WriteToThem asks you to input your postcode, then shows you who represents you politically, from councillors to MPs and MEPs.

How does it do this? By sending the postcode to MapIt, which checks which boundaries it falls within (ward, constituency, borough, etc), then returns those areas so that the WriteToThem code can display the politicians for each one.

Similarly, our site FixMyStreet takes the geographic point where a user has spotted a problem such as fly tipping or a pothole, and asks MapIt to match it to the right council to deal with it.

So, in a nutshell: MapIt is a system that sends data about administrations and other location-related data in response to requests from a website or service.

This is useful if you are building services that require these data, for example, to identify things like:

In technical terms MapIt is classed as an API which stands for Application Programming Interface. It allows an external service to query data held in a database and return results. This removes the need to build such a database yourself – you can simply use MapIt in your application or site.

Other examples

We’ve seen how MapIt works for us – now let’s take a look at how others are using it. was an innovative marketing site for the novel Capital by John Lanchester, released by Faber in 2012.

Pepys Rd used data you input and live data to reflect on the role of markets and infrastructure in our lives, signing you up to a ten-day adventure via email. The site’s developers, Storythings, used MapIt for a number of the components, with its location data providing real-time story elements for the project.

GOV.UK – the UK Government’s digital portal – uses an installation of MapIt to enable visitors to its website find the right information on local public services based on their postcode.

See their page on local councils and services: from applying for an allotment to checking when your recycling is collected, MapIt connects you to the information relevant to your area.

Prostate Cancer UK used MapIt as part of their campaigning tool: input your postcode and you’ll see what provision is available for those with prostate cancer in your Heath Board area.

MapIt can do this because it knows the boundaries of each CCG (Clinical Commissioning Group) region. When data is personalised like this, users can see its relevance to their own lives, and it becomes a very powerful campaigning tool.

Inputs and outputs

MapIt matches points and boundaries. It can be used with:

It can take any of those and give you:

It can deal with multiple areas at once, so for example you can get information about every type of area within a category (e.g. city council) or containing a given string in its name (e.g. “Leicester”).

You can even query historical data, by calling a list of updates to MapIt information, with a unique number for each update (or “generation”).

Boundary changes

MapIt generally holds and returns current administrative boundaries, and boundary changes come into effect on the day of the relevant election. Ordnance Survey sometimes publish forthcoming boundary changes in advance, and in such cases we will try and import these and make them available in some manner, but they are not published in the same format as the normal data.


Note that MapIt works by matching the centre point of the given postcode to the boundaries it sits within. In a few rare cases (affecting perhaps half the residents in approximately 0.2% of postcode areas), where a postcode area straddles a boundary, this will result in a return of the neighbouring ward or constituency.