If you build anything for UK users, like checkout forms, delivery zones, store finders or "within 10 miles" searches, you need postcode data. UK PostcodeKit wraps the official OS Code-Point Open dataset, covering every postcode in Great Britain, in a fast API.

curl -G "https://uk-postcodekit-postcode-lookup-nearest-distance.p.rapidapi.com/lookup" \ --data-urlencode "postcode=SW1A 1AA" \ -H "X-RapidAPI-Key: YOUR_RAPIDAPI_KEY" \ -H "X-RapidAPI-Host: uk-postcodekit-postcode-lookup-nearest-distance.p.rapidapi.com"

You get the latitude and longitude, eastings and northings, and the country, district and ward codes.

Endpoints

  • /validate: checks the format and whether the postcode exists, and normalises it (bs3 1dh becomes BS3 1DH).
  • /autocomplete?q=SW1A 1: suggestions as the user types.
  • /nearest?lat=51.5246&lng=-0.112&radius=200: the postcodes nearest a point.
  • /distance?from=SW1A 1AA&to=EH1 1YZ: straight-line distance, which is 533.79 km here.
  • /outcode?outcode=BS3: the centre point and stats for a district.

For AI agents

It's also an MCP server at https://uk-postcodekit-postcode-lookup-nearest-distance.p.rapidapi.com/mcp.

Contains OS data © Crown copyright and database right. Contains Royal Mail data © Royal Mail copyright and database right. Licensed under OGL v3.0. There's a free plan. UK PostcodeKit on RapidAPI