The Hathi Trust is a partnership of 60 major research institutions and libraries working to ensure that the cultural record is preserved and accessible long into the future. Its goal is to build a reliable and increasingly comprehensive digital archive of library materials converted from print that is co-owned and managed by a number of academic institutions.
The Internet History Sourcebooks Project is a collection of public domain and copy-permitted historical texts presented cleanly (without advertising or excessive layout) for educational use.
The Post-Reformation Digital Library (PRDL), is a "webliography" of digital resources from digital libraries in Europe and North America. A very helpful metaguide, though it requires a healthy measure of prior knowledge to navigate the collection effectively. Use the sidebar index for quick access.
The Christian Classics Ethereal Library
A digital library of theological texts. It contains primarily patristic, medieval, and Reformation era texts, but also has post-Reformation items as well.
British History Online
British History Online is the digital library containing some of the core printed primary and secondary sources for the medieval and modern history of the British Isles.
An image database of medieval and renaissance manuscripts that unites scattered resources from many institutions.
This resource searches the holdings of the Meeter Center for Calvin Studies, a research center that seeks to hold in print a copy of every possible piece of research, published or otherwise, on the Reformed branch of the Reformation, but they also collect materials more broadly related to the Reformation. Search results yield location and call numbers related to their particular collection. Resources are not available digitally. This database is best viewed, therefore, as a searchable bibliography for the identification of resources to then be obtained through other means.