https://anavathmis.eu/?lang=en
The Institute of Historical Research (IHR) of the National Hellenic Research Foundation (NHRF) provides open access to 16 databases concerning Byzantine History and especially Byzantine Greece: https://anavathmis.eu/?lang=en.
Based on the scrutiny of a large body of primary and secondary sources by members of the Section of Byzantine Research of the IHR/NHRF and associated scholars, the databases provide various search possibilities in certain types of texts (historiography and hagiography) and in specific topics (e.g. gastronomy, bookbinding, imported ceramics, raw materials, natural resources and agricultural products, domestic and wild fauna, Greek merchants), as well as a catalogue of the Byzantine documents kept in the archives of the monastery of Saint John the Theologian in Patmos, notes found in manuscripts of the same monastery, the diplomatic transcriptions of Greek post-Byzantine documents kept in the archives of the monasteries of Mount Athos, a gazetteer of late Byzantine conflicts, a prosopographical index (for the Venetian colonies in Greece), a catalogue of western religious orders in Greece. Of special note is the “Kyrtou Plegmata” platform, which offers search possibilities in the trade and communication networks in and around Greece from Prehistory to the 19th c.
The IHR/NHRF also provides open access to a number of e-books regarding Byzantine History: https://anavathmis.eu/e-books/?lang=en#1573422809019-ffd3837c-0760