This is a massive search hub for articles in the science and humanities. Many people do not have access to latest research, as knowledge is monopolized in the universities and publishing companies. This allows independent research to be conducted without the need to pay for individual articles or journals.

Internet Archive: https://archive.org/

Non-profit organization houses millions of books, videos, and internet pages. Great tool for looking at older material and has a very good search filter, allowing to find key words and passages that would take longer to find in a traditional book.

Standford Philosophical Encyclopaedia: https://plato.stanford.edu/index.html

As I studied philosophy as an undergraduate, SPE is a great resource for beginners and those interested in doing research. Articles are updated regularly by academics and provides good articles at the end for continued lines of inquiry.

JSTOR: https://www.jstor.org/

A traditional academic journal, however, they provide 100 free articles a month for anybody with an account.

Google Classroom: https://edu.google.com/workspace-for-education/products/classroom/