Some publishers currently offer free or easier access to journals or e-books:
AEA - American Economic Association
Free access to journals until June 30, 2020
Bloomberg Media Offers College Students Worldwide Free Digital Subscriptions for Three Months, starting April 22
Cambridge University Press
Free access to over 700 text books until May 31, 2020
Free access to 256 text books for 90 days, until June 20, 2020
Energie.de - Portal der Energiewirtschaft
EW, Netzpraxis, ET and Euroheat & Power from vol. 2019, free access until the end of 2020
JoVE education video
Free access to many videos until June 15, 2020
Journals until June 30, 2020
Complete contents (e-books, journals, text books etc.) at first until March 31, 2020
University publishers as well as other participating publishers, journals and e-books, e.g. Duke, Johns Hopkins, MIT, Princeton etc.
Oxford University Press
Free access to "COVID-19 resources" (articles from books and journals that are related to Covid-19)
ProQuest E-Book Central
Unlimited simultanous access to many e-books until June 15, 2020
Free access to a range of essential textbooks from all disciplines.
University Press Community
More than 80 publishers open up a wide variety of resources, books, and journals.
All journals from volumes 2001 onwards, until June 30, 2020
Norwegian Database Idunn
Free access while libraries are closed
ACM Digital Library
ACM DL is now open, and will continue that way through June 30, 2020.
DBIS: List of licensed databases that unlock more contents (for users of libraries with an existing license)