Software from the Postcodes.io project is freely available for commercial and non-commercial use under the MIT licence.
Postcodes.io ingests a dataset from the Office for National Statistics called ONS Postcode Directory (ONSPD). ONSPD is updated quarterly. This dataset carries a separate licence to Postcodes.io.
ONSPD carries different licensing rules for Great Britain and Northern Ireland data.
Great Britain data from ONSPD carries an Open Government Licence. Information on the Open Govnerment Licence is available at nationalarchives.gov.uk.
Northern Ireland data (i.e. postcodes beginning "BT") carries a different licence depending on use case.
Both Great Britain and Northern Ireland data is free for non-commercial use.
Data from Great Britain may be used freely subject to the Ordnance Survey (OS) OpenData licence.
Data from Norther Ireland (postcodes beginning with
BT) may be used under the terms of the ONSPD licence. Non-commercial use is free. Commercial use requires a licence from NI & Property Services.
Both Great Britain free for non-commercial use under the Open Government licence.
Northern Ireland data is permitted for Internal Business Use under the Northern Ireland End User Licence available from ONS. All other commercial usage requires a separate licence from Land and Property Services Northern Ireland.
More information on licensing can be accessed on the Office for National Statistics licensing page.