Address Lookup API / ONS Postcode Directory

ONS Postcode Directory

The Office for National Statistics assigns geographies to postcodes using the ONS Postcode Directory (ONSPD).

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Key features of ONSPD

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Adding geospatial data to postcodes

ONSPD is a dataset for business and public bodies looking to reference their spatial data by postcode.

As well as routing and delivering mail, Postcodes can provide boundaries for thematical mapping.

ONSPD links all current and terminated UK postcodes to a wide range of administrative, health, and other geographic areas in which each postcode falls using a point-in-polygon methodology. It helps support the production of area-based statistics from postcoded data.

This data can also be displayed on a map using postcode centroids or postcode-based polygons.

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Adding geospatial data to postcodes illustration

How ONS Postcode Directory can help your organisation


  • Accurate service planning
    Use additional geospatial fields such as Clinical Commissioning Group codes to accurately plan and deliver services
  • Data analysis
    Mapping statistical data by postcode allows postcode area-based analysis
  • Provide local area information
    Postcode level geodata allows you to turn postcode areas into coordinates, or search postcodes by location
  • NHS technology
    The NHS administrative data provided by ONSPD can assist companies that create technology for the NHS with planning and delivering their services

Use Postcoder to access ONS Postcode Directory data with our simple and secure API

Postcoder is hosted on a leading cloud platform in the UK and Ireland, and is supported by our friendly team of addressing specialists.

  • Secure HTTPS connection
  • GDPR compliant data processing
  • 99.99% API uptime
  • 350ms real-world response time
  • Free technical support and licensing guidance
  • Find out more about the power of Postcoder

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