Crack ACT
Crack ACT offers an extremely large databank of officially released ACT/PACT tests, answers, and explanations.
Crack SAT
Crack SAT offers an extremely large databank of officially released SAT/PSAT/NMSQT tests, answers, and explanations.
Princeton Review
Princeton Review offers multiple free SAT/ACT online prep options, including a full-length practice test and free online courses on testing strategies. After completing an online diagnostic test, Princeton Review gives the user an in-depth report that displays strengths and weaknesses.
Kaplan
Kaplan has multiple free SAT/ACT prep options available, including practice tests and pop quizzes containing official SAT/ACT test questions.