The Mozarteum Foundation Salzburg (MFS) currently holds approximately half of the known letters and documents of the Mozart family, thus possessing the largest collection of this kind worldwide. The majority of the circa 700 documents consist of the handwritten correspondence between Wolfgang Amadé Mozart and his father, Leopold. Also included are numerous letters from Constanze Mozart (most in the hand of her second husband, Georg Nikolaus von Nissen) as well as letters from both of Mozart's sons, Carl Thomas and Franz Xaver Wolfgang. All known and accessible letters from Leopold and Wolfgang Amadé Mozart have been published by Wilhelm A. Bauer and Otto Erich Deutsch in the 1962 Complete Edition: Briefe und Aufzeichnungen.
In addition to those known manuscripts previously published in the Complete Edition, the MFS also holds an extensive and fascinating document collection which extends its scope well into the 19th century. This substantial collection includes not only letters but pages from the "guest books" of the Mozart family, various reciepts, as well as documentation from the estate of several family members including the sisters of Constanze, Sophie Haibel and Aloysia Lange, and Mozart's own sister, Maria Anna von Berchtold zu Sonnenburg. The collection boasts the "Nissenkollekteen", the collection of documents used by Nissen for the preparation of his Mozart biography. Numerous pages concerning the history surrounding the Mozarteum Foundation and the "Mozart Ehrung" (dedication of the Mozart monument), part of the Aloys Fuch estate as well as letters and documents related to Mozart and persons influential in Mozart research complement this extensive collection of over 600 documents in the archive of the ISM.
In cooperation with the Packard Humanities Institute, Los Altos/ California, the ISM has recently digitalized all of these historical letters and documents at the highest technical standard. The goal of this project is the online publication of all letters and documents related to the Mozart family as well as related letters and documents spanning from 1740 (when Leopold Mozart arrived in Salzburg ) to 1881 (the founding of the International Mozarteum Foundation) as both image and text. The collection will be accessible to the public at large.
Beginning with its own resources, the MFS hopes to expand this online publication step by step, incorporating all documents, even those which are missing or which only appear partially in the Complete Edition. The long term goal of the project is the publication of a new Bauer/Deutsch Complete Edition of Letters and Documents. Through this abitious project, the Foundation hopes to draw interest and encourage owners of additional Mozart manuscripts to share their "treasures" in this online platform.
The website of the Digital Mozart Edition (DME)serves as a platform to present research results from other Mozart projects.