https://www.varsitytutors.com/sat-practice-tests 

https://www.khanacademy.org/test-prep/sat 

https://www.chegg.com/test-prep/sat 

https://www.collegeboard.org/ 

http://www.number2.com/ 

http://improvesatscore.com/ 

http://momentrix.com

https://www.exam2jobs.com/ 

https://www.chegg.com/test-prep/act 

https://www.collegeboard.org/ (SAT & PSAT - college entrance exam)

http://www.act.org/ (ACT - college entrance exam)

https://kaplan.com/ (College entrance exam preparation - includes PSAT)

http://www.ets.org/ (Exam preparation - includes AP exams)

https://www.essayedge.com/ (Preparation for essay portion of college entrance exams)

https://www.march2success.com/main/courses (free SAT/ACT prep)