Karelsprivilege is a legendary privilege that Charlemagne allegedly paid to the Frisians led by Magnus Forteman to thank them for the support that was given to his attack on Rome. Since the 13th century, the Frisians regularly mentioned Karelsprivilege in legal and historical works. The authenticity of the privilege has been heavily contested, especially after the Middle Ages. The privilege formed the basis of the so-called Frisian freedom. It was recognized as genuine by a number of Holy Roman emperors. An affirmation and recognition of the privilege was given by Emperor Conrad II in 1039.
The original has been lost. According to tradition it was inscribed on the wall of a church, which could be the church of Almenum, Ferwoude or Oldeboorn. Copies were made and circulated during the Middle Ages. Some or all of these copies were likely forgeries.
In the Middle Ages, only the original, and undamaged sealing wax impressions, were accepted as valid. Forged documents were common, and a well-organized archive of treaty documents that could serve as a reference did not exist. Medieval literature mentioned a link between the Frisian eagle as a heraldic charge in coats of arms and the Karelsprivilege. This is unclear because in the time of Charlemagne there were no family or regional coat of arms existing, but it could have been used as a banner in that period.
Other names used for this charter are: Magnuskerren, Friezenprivilege, Vrijheidsprivilege, Libertas Frisonica or Previlegii Frisiorum Caroli Magni.