Al's Notebook: 

https://www.alsnotebook.com/

Evans' pKa Table: 

Download PDF file 

e-EROS: 

https://onlinelibrary.wiley.com/doi/book/10.1002/047084289X

IUPAC Compendium: 

https://goldbook.iupac.org/

Name Reaction List: 

http://www.monomerchem.com/display4.html

NIST Chemistry WebBook: 

https://webbook.nist.gov/chemistry/

Not Voodoo: 

https://www.chem.rochester.edu/~nvd/

Mass Spec Calculator: 

https://www.sisweb.com/mstools/isotope.htm

Optical Rotation Calculator: 

http://www-jmg.ch.cam.ac.uk/tools/magnus/optRot.html

Organic Synthesis: 

http://www.orgsyn.org/

Periodic Table: 

https://www.webelements.com/

PDB (Protein Data Bank): 

https://www.rcsb.org/pdb/home/home.do

Synthesis Literacy Group: 

https://chem.columbia.edu/department-life/student-led-seminars/synthesis-literacy-group/

SBDS (Spectral Database): 

https://sdbs.db.aist.go.jp/sdbs/cgi-bin/cre_index.cgi

Web of Knowledge: 

https://apps.webofknowledge.com/