Sci-Hub - They fight inequality in knowledge access across the world. The scientific knowledge should be available for every person regardless of their income, social status, geographical location and etc. Their mission is to remove any barrier which impeding the widest possible distribution of knowledge in human society.
Internet Archive - Non-profit library of millions of free books, movies, software, music, websites, and more.
media.ccc.de - This site offers a wide variety of video and audio material distributed by the Chaos Computer Club.
Queer Zine Archive - First launched in November 2003 in an effort to preserve queer zines and make them available to other queers, researchers, historians, punks, and anyone else who has an interest DIY publishing and underground queer communities.
Library Genesis - A free online library of various literature and nonfiction, including many textbooks.