Tools:

SciHub: - You will find full research papers here
sci-hub.is
sci-hub.se
sci-hub.se

How to use Sci-hub to get academic papers for free
https://emilkirkegaard.dk/en/?p=7165

More alternatives:
https://paperhub.ir/
https://freepaper.me/
https://scinapse.io/
https://core.ac.uk/
https://www.semanticscholar.org/
https://www.researchgate.net/
https://www.academia.edu/
https://www.libkey.io
https://cyberleninka.org

Use to find DOI number
https://search.crossref.org

Get books:
Z library
https://z-lib.org/
LibGen:
http://gen.lib.rus.ec/

How to download ebooks from Library Genesis (libgen) for free
http://emilkirkegaard.dk/en/?p=7172

To view articles behind paywalls
https://outline.com

Great translator:
https://www.deepl.com/translator

Find research papers:
https://scholar.google.com

Archiving tools:

Archive.is (or .li .fo, w/e)
Perma.cc
https://web.archive.org
https://archive.st