My medieval manuscripts resources are listed here more as a personal reminder of digitized collections/various topics of interest/anything else I have used that I don't want to forget about :)
Maybe they will be of interest to you, too!
Links open a new window for you.
** Starred links mean that on these sites I have found free/royalty free/public domain/reusable images or the option of embedded content that can be shared on your site. There may be images on these sites that are not reusable, however - so double check the copyright status of any image you want to use.
The British Library Digitised Manuscripts - medieval, global, tons to browse
Digital Bodleian - Bodleian Libraries and Oxford college libraries
Cambridge Digital Libary - another rich resource
** Wren Digital Library - digitised collections from the Library of Trinity College, Cambridge
** e-codices - virtual manuscript library of Switzerland
Medieval Manuscripts of France and England - Bibliothèque Nationale de France and British Library partnership with manuscripts from 700 - 1200.
**Parker Library on the Web - Parker Library at Corpus Christi College, Cambridge, a digital exhibit from Corpus Christi College and Stanford University Libraries
Harvard Library Botanical Illustrations - from the Botany Libraries
Harvard Library Medieval and Renaissance Manuscripts - from Houghton Library
Medieval and Renaissance Manuscripts - the Morgan Library and Museum
** The Walters Art Museum - digitised manuscripts from the Walters Art Museum, Baltimore
** The J. Paul Getty Museum - 9th to 16th centuries, lots to browse here
** Wellcome Collection - search under the "images" tab to find pictures of trees, manuscripts, scrolls - or anything else!
The Schøyen Collection - a fascinating private collection of world manuscripts
Society of Antiquaries - Magna Carta, Winton Domesday. The Society also has a section about Kelmscott Manor, the retreat of William Morris, which it owns (and I have visited, super place!)
** Phaidra - the University of Paduva Library System - art, history, culture, botanical gardens, illustrated herbals ... a superbly built site and well worth a visit!
DigiVatLib - the Digital Vatican Library
Belgica - digitised collections from KBR (formerly the Royal Library of Belgium)
British Library Glossary - glossary for the British Library Catalogue of Illuminated Manuscripts
Introduction to Medieval Books - University of Nottingham
The Making of Medieval Manuscripts - an excellent online exhibition by the Parker Library on the Web.
Medieval Manuscript Repair - Atlas Obscura
Medieval Scrolls - an Introduction
Books to borrow from the Internet Archive - requires registration:
Michelle P. Brown - A Guide to Western Historical Scripts from Antiquity to 1600
J.J.G. Alexander - The Decorated Letter
Christopher de Hamel - A History of Illuminated Manuscripts
Online/downloadable titles from MetPublications, the Metropolitan Museum of Art:
Melanie Holcomb - Pen and Parchment: Drawing in the Middle Ages
Timothy B. Husband & Margaret Lawson: The Art of Illumination: The Limbourg Brothers and the Belles Heures of Jean de France, Duc de Berry
Latin Paleography - from Roman Book Capital through to Uncial, Semi-Uncial, Insular scripts, Visigothic, Carolingian, Gothic, and everything in between, this is a great series of articles from the Vatican Library.
History of Information - the "History of Information and Media through Timelines".