We originally featured this resource in the 10-13-2017 Scout Report. Since then it has added several new components, including Early Music Sources PIE ("Please in English"), which "aims to take sources that were never translated, and in some cases never published, and publish them online for free, in English."
Founded in 2014 by music scholar and composer Elam Rotem and musician and musicologist Joerg-Andreas Boetticher, Early Music Sources is designed to "simplify the access to the vast amount of online early music sources." As of this write-up, this resource contains two databases and a YouTube channel. The databases allow visitors to explore over 1,500 articles, books, and manuscripts published between the 15th and 20th centuries. Visitors can conduct a text search of these items or browse by category, such as Basso Continuo-English; keyboard instruments; or tuning and temperament. Many of these materials have been digitized and can be accessed for free. Meanwhile, the Iconography Database, which "focuses on depictions of music-making that may record aspects of contemporaneous performance practice," features 152 fascinating works of art, which visitors are invited to browse by Century, Instrument, or Category. Finally, visitors won't want to miss the site's delightful YouTube channel, which offers accessible and engaging educational videos about a variety of topics related to the early music movement.