Harry Metcalfe and Richard Pope recently let us know about their new postcode lookup API, named after Ernest Marples, the Postmaster General who introduced the Postcode:

More about the service:

Post codes are really useful, but the powers that be keep them closed unless you have loads of money to pay for them. Which makes it hard to build useful websites (and that makes Ernest sad).

So we are setting them free and using them to run and Jobcentre Pro Plus. We’re doing the same as everyone’s being doing for years, but just being open about it.

There are now several free sources of UK postcode data – including New Popular Edition Maps and Free the Postcode. For other sources of postcode data elsewhere in the world, see:

If you know of any other postcode-related open datasets, we’d love to hear about them!

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Dr. Jonathan Gray is Lecturer in Critical Infrastructure Studies at the Department of Digital Humanities, King’s College London, where he is currently writing a book on data worlds. He is also Cofounder of the Public Data Lab; and Research Associate at the Digital Methods Initiative (University of Amsterdam) and the médialab (Sciences Po, Paris). More about his work can be found at and he tweets at @jwyg.