Biblicalstudies.org.uk: free online access to thousands of (older) theological books and articles.
Brill Open Access Journal Articles
Cambridge Papers towards a Biblical Mind
Christian Classics Ethereal Library
Directory of Open Access Journals (Religion)
Doab (Directory of Open Access Books)
Encyclopaedia Judaica: available for free in PDF online. Search using this format ‘Encyclopaedia Judaica vol.01 PDF’ and look for successive volumes .02, .03, etc.
Flower Pentecostal Heritage Center: the largest Pentecostal archive in the world with a digital publication search function
JSTOR Free Personal Account: 100 articles online for free every 30 days
Monergism: free online collection of Reformed Christian resources
Open Access Digital Theological Library
Project Gutenberg: free online resources that are in the public domain (not protected by copyright anymore)
ReligTres. Please note the following from the developers of this resource: The new reality of information organization and search systems dictate the use of post-synthesized indexing tools and more specifically thesauri for the thematic description of any kind of information material. Thus, an attempt is being made to construct a Thesaurus of Theological Terms (TTH or ReligTres) that will describe thematically and at the same time give easy and precise access to information material that belongs to the field of theology, with particular emphasis on Orthodox Christian theology. The Thesaurus of Theological Terms (TTH or ReligTres) was originally structured as a monolingual Greek thesaurus with links to corresponding English terms and classification numbers in the Dewey Decimal Classification (DDC). However, in order to be used by non-Greek-speaking users, a parallel hierarchy of English terms has been developed automatically. This is the first step towards a fully bilingual thesaurus. Please be aware that the English terms have arisen as equivalents to the Greek terms and that is why the English hierarchical tree may have linguistic and terminological weaknesses. The English hierarchy should be understood only as corresponding the Greek one and not as an autonomous one, simply providing a bridge to the English-speaking users.
Sefaria: home to 3,000 years of Jewish texts. Free access to texts, translations, and commentaries
Wellcome Collection: register for their free library membership then access remote online resources