The HDS collection, which is part of the UK Data Archive (UKDA), brings together over 650 separate data collections transcribed, scanned or compiled from historical sources. The studies cover a wide range of topics from the seventh century to the twentieth century. Although the primary focus of the collection is on the United Kingdom, it also includes a significant body of cross-national and international data collections. In addition, the HDS also enriches and enhances selected data collections by developing thematic special collections where there is a critical mass of related data collections. Current special collections include: Census enumerators’ books, including the entire 1881 Census for England, Wales and Scotland; Poll Books, including the Westminster Historical Database, 1749-1820; British and Irish nineteenth and twentieth century statistics, including histpop – the online historical populations reports website; wage and price time series including the European State Finance Database; local history including the Digital Library of Historical Directories, 1750-1919; and prosopography including the COEL Database: Continental Origins of English Landowners, 1066-1166.

The HDS does not have any specific APIs, although general advice to data creators is available at: http://hds.essex.ac.uk/history/create/create-advice.asp