The London customs records of the Middle Ages represent a central source of economic history and finance for the English crown. These records trace the careers of individual long distance traders in European foreign trade and trades in various groups: Hanseatic merchants, Venetians, Spaniards, Portuguese and Dutch, The edition of the customs files is planned on about 40 volumes. The first volume contains a detailed introduction to the complete edition and will be published in print and in Open Access. All other volumes are successively in open access on the website of the Hanseatic History Association (www.hansischergeschichtsverein.de) made accessible.