There are a number of ways of locating medieval manuscripts: by library catalog, by online sites (which are often library catalogs), and through listings of incipits.
Pecia offers a long list of libraries and online sites with digitized manuscripts.
A select Listing of Sites
Digital Scriptorium (DS) is a growing organization of institutional partners with collections of medieval and Renaissance manuscripts. DS provides an online union catalog of these collections and thus unites scattered resources from many institutions into an international tool for teaching and scholarly research. As a digital image repository, the DS website allows users to verify with their own eyes descriptive metadata about places and dates of origin, scripts, artists, and decoration.
Friedrich Stegmueller's multi-volume Repertorium Biblicum Medii Aevi
The RBMA contains thousands of Latin religious texts, including commentaries and other theological writings and lists their manuscripts and editions.
The principal objective of Europeana Regia is to reconstruct, in the form of a virtual library, the most important European royal collections of documents from the Middle Ages to the Renaissance. Managed by the Bibliothèque nationale de France (BnF), Europeana Regia unites five European libraries—the Bayerische Staatsbibliothek, Munich (BSB), the Universitat de València Biblioteca Històrica (BHUV), the Herzog August Bibliothek, Wolfenbuttel (HAB), and the Koninklijke Bibliotheek van België-Bibliothèque royale de Belgique (KBR)—and encompasses almost nine hundred manuscripts that are representative of the political, cultural and artistic history of Europe.
The Edgar J. Goodspeed Manuscript Collection comprises 68 early Greek, Syriac, Ethiopic, Armenian, Arabic, and Latin manuscripts ranging in date from the 5th to the 19th centuries. The acquisition of these hitherto unknown manuscripts was spearheaded by Edgar J. Goodspeed in the first half of the twentieth century in order to support new scholarship in the humanities. The University of Chicago Library is providing a unique digital resource based on this collection. All 68 New Testament manuscripts have been digitized in their entirety and are presented with high-quality zoomable images through an interface that supports browsing within individual manuscripts and across the collection.
The Manuscriptorium project is creating a virtual research environment providing access to all existing digital documents in the sphere of historic book resources (manuscripts, incunabula, early printed books, maps, charters and other types of documents). These historical resources, otherwise scattered in various digital libraries around the world, are now available under a single digital library interface. The service provides seamless access to more than 5 million digital images.
The Monastic Manuscript Project is a database of descriptions of manuscripts that contain texts relevant for the study of early medieval monasticism, especially monastic rules, ascetic treatises, vitae patrum-texts and texts related to monastic reforms. The purpose is to offer a tool for reconstructing not only the manuscript dissemination of early medieval monastic texts but also to give access to the specific contexts in which a text appears. Most pages provide links to a number of web resources, such as manuscript catalogues, online texts and translations, digitized manuscripts and repertoria. Manuscript descriptions are usually based on published manuscript catalogues and secondary literature.
The Schoenberg Database of Manuscripts aggregates observations of premodern manuscripts drawn from over 12,000 auction and sales catalogues, inventories, catalogues from institutional and private collections, and other sources that document sales and locations of these books from around the world. Using thirty-six possible fields, entries in the Schoenberg Database of Manuscripts (SDBM) record data from observations made in these sources and assist researchers in locating and identifying particular manuscripts, establishing provenance, and aggregating descriptive information about specific classes or types of manuscripts.
Cranz, F. Edward (Ferdinand Edward) comp. A microfilm corpus of the indexes to printed catalogues of Latin manuscripts before 1600 A.D. 38 Microfilm reels. New London, Conn. : [Connecticut College?] : Obtained from the Connecticut College Bookstore, 1982.
Bibliothèque royale de Belgique. Section des manuscrits. Catalogue des manuscrits de la Bibliothhque royale de Belgique. Bruxelles, H. Lamertin, 1901-1909 ; Renaux, Des presses de J. Leherte Courtin, 1919-1948. 13v.
Cambridge University Library. A catalogue of the manuscripts preserved in the library of the University of Cambridge. 5v. Cambridge, University Press, 1856-1867. All volumes are available via the Internet Archive.
Parker Library Of Corpus Christie College, Cambridge, on the Web Parker Library on the Web is a multi-year undertaking of Corpus Christi College (Cambridge), the Stanford University Libraries and Cambridge University Library, to produce a high-resolution digital copy of every imageable page of most manuscripts in the library
Robinson, Pamela. Catalogue of dated and datable manuscripts c. 737-1600 in Cambridge libraries. 2v. Cambridge [Cambridgeshire]; Wolfeboro, N.H., USA : D.S. Brewer, 1988.
John Rylands Library. A descriptive catalogue of the Latin manuscripts in the John Rylands library at Manchester . 2v. Manchester, The University press ; London ; New York, Longmans, Green & company, 1921.
CALAMES-Catalog of archives and manuscripts in French academic and research libraries
Codices Electronici Ecclesiae Coloniensis--full digitization of medieval manuscripts in the Episcopal and Cathedral Library of Cologne.
Manuscripta Mediaevalia : a portal for medieval manuscripts in German libraries.
Bayerische Staatsbibliothek. Catalogus codicum manuscriptorum Bibliothecae Monacensis. Munchen, In kommission der Palmschen buchhandlung, 1866- . Available online at the Internet Archive.
Bibliotheca Palatina Digital One of the consequences of the Thirty Years War was that the most important collection of books in the 17th century Holy Roman Empire, the Bibliotheca Palatina, was divided between two principal locations: Heidelberg and the Vatican. Since 2001, Heidelberg University Library has been working on several projects that aim to digitize parts of this great collection, the final goal being a complete virtual reconstruction of the “mother of all libraries.”
MANUS Online conatins catalogue descriptions and digital images of manuscripts, private papers and archives held by Italian public, private and ecclesiastical libraries. The census, launched by ICCU—Istituto Centrale per il Catalogo Unico—in 1988, aims to list and catalogue manuscripts written in Latin alphabet from the Middle Ages to date, including private papers and literary archives.
Digital Vatican Library The project aims to digitize the entire Library’s collection of manuscripts: 80,000 codices (excluding the archival units) mostly from the Middle Ages and the Humanistic Period.
Hague. Koninklijke bibliothek. Catalogus codicum manuscriptorum Bibliothecae regiae. Hagae Comitum, 1922.
Universidad de Barcelona. Biblioteca. Inventario general de manuscritos de la Biblioteca universitaria de Barcelona . Madrid, Direcciones generales de enseanza universitaria y de archivos y bibliotecas, Servicio de publicaciones de la Junta ticnica, 1958- . 4v.
Catedral (Cordoba, Spain). Biblioteca. Catalogo de los manuscritos e incunables de la Catedral de Cordoba. Salamanca: Universidad Pontificia [de Salamanca], 1976.
Martin Abad, Julian. Manuscritos de Espana: guma de catalogos impresos. Madrid: Arco Libros, 1989.
Stiftsbibliothek Sankt Gallen. Verzeichniss der Handschriften der Stiftsbibliothek von St. Gallen. Halle : Buchhandlung des Waisenhauses, 1875.
Directory of Institutions in the United States and Canada with Pre-1600 Manuscript Holdings by Melissa Conway and Lisa Fagin Davis. The Directory of Institutions is the first part of a continuation of the Census of Medieval and Renaissance Manuscripts in the United States and Canada, published in 1935 and 1937, and its 1962 Supplement.
Beinecke Rare Book and Manuscript Library. Catalogue of medieval and renaissance manuscripts in the Beinecke Rare Book and Manuscript Library, Yale University. 3v. Binghamton, N.Y.: Medieval & renaissance Texts & Studies, 1984- .
The Houghton Library's distinguished collection of medieval and Renaissance manuscripts represents a significant resource for the study of the Middle Ages and the Renaissance in Western Europe. Assembled through gifts and purchase over the past two centuries, this collection includes works in Latin, Greek, and most of the vernacular languages of Europe that are the primary sources for the study of the literature, art, history, music, philosophy, and theology of the periods.
Houghton Library. Catalogue of Medieval and Renaissance manuscripts in the Houghton Library, Harvard University. Binghamton, N.Y. : Medieval & Renaissance Texts & Studies, 1995- .
Huntington Library and Art Gallery. Guide to medieval and Renaissance manuscripts in the Huntington Library. 2v. San Marino, Calif. : The Library, 1989.
The Monastic Manuscript Project is a database of descriptions of manuscripts that contain texts relevant for the study of early medieval monasticism, especially monastic rules, ascetic treatises, vitae patrum-texts and texts related to monastic reforms. We provide lists of manuscripts for each of these texts, which are linked to manuscript descriptions. The purpose is to offer a tool for reconstructing not only the manuscript dissemination of early medieval monastic texts but also to give access to the specific contexts in which a text appears.
Guided by the vision of its founder, Lawrence J. Schoenberg, the mission of SIMS at Penn is to bring manuscript culture, modern technology and people together to bring access to and understanding of our intellectual heritage locally and around the world.
This Web site contains complete sets of high-resolution archival images of manuscripts from the collection of the Walters Art Museum, along with machine-readable TEI P5 descriptions and technical metadata, released for free under a Creative Commons CC0 license for anyone who wants to use them.
Virtual Hill Museum and Manuscript Library (vHMML) The Hill Museum and Manuscript Library houses the world's largest collection of images of manuscripts from Europe, Ethiopia, the Middle East, and India. HMML's teams have been photographing manuscripts since 1965. These holdings can be searched through this website.