The corpus of charters written in Old Frisian contains circa 1250 documents, written between roughly 1400 and 1550 AD. A handful of charters stems from the 14th century. Charters in the Frisian language form a subset of charters written in medieval Frisia (between the rivers Vlie and Lauwers): they were also written in Latin or Dutch.
Written charters arose relatively late in Frisia. Nevertheless, they offer valuable materiaal for all aspects of medieval Frisian society. Oebele Vries (in his book Ferban 2021) distinguishes 41 categories of Old Frisian charters. The most frequently attested category is that of a purchase. When land or other goods were sold, a charter was drawn up to write down this transfer of property so that the buyer could prove it was his.
The Frisian charters have been edited under the title Oudfriese Oorkonden in the series Oudfriese Taal- en Rechtsbronnen by Pieter Sipma (vols 1-3) and Oebele Vries (vols. 4 and 5). Vol. 5 appeared outside of this series. The numbers in the field ‘Doc id’ indicate the vol. and the number of the charter in that edition. So OOR10009 stand for Oudfriese Oorkonden vol. 1, charter nr. 9, and OOR20225 for Oudfriese Oorkonden vol. 2, charter nr. 225.
The photographs of the charters have been made by Tresoar Leeuwarden, by the Frysk Ynstitút or by Historisch Centrum Leeuwarden. Those of the former two organisations were scanned by Willem Maas (Fryske Akademy) in 2013 and linked to the charter texts by Ewoud van Aalst MA in 2024.