Postcodes.io

About Postcodes.io

Postcodes.io is an open-source API for validating, searching, and geolocating UK postcodes. It provides administrative and geospatial data tied to postcodes, including region and boundary details, and supports methods such as postcode validation, nearest-postcode lookup, outward code lookup, autocomplete, and bulk reverse geocoding of latitude/longitude coordinates into nearest postcode areas. Data is updated with information from Ordnance Survey and the Office for National Statistics as it becomes available.

The project is MIT licensed and maintained on GitHub, where it can be forked, self-hosted, or contributed to. It is aimed at developers building applications that need UK postcode lookup and geocoding functionality.

For applications requiring broader coverage across the whole UK and its territories, international datasets, rooftop geocodes, UPRNs, property-level precision, daily data updates from Royal Mail and other providers, or dedicated support, the page points to a related paid service, Ideal Postcodes.

Key features

• UK postcode search, validation, and geolocation
• Bulk reverse geocoding of lat/long coordinates into nearest postcodes
• Retrieve geographical and demographic data (region, boundary, administrative details) for a postcode
• Autocomplete and outward code lookup
• Open source, MIT licensed, self-hostable

Frequently asked questions