There are a variety of free SAT/ACT test prep resources available.
Free Test Prep
Offers free test prep for both the ACT and SAT. Must register but not many required questions. Will receive emails that track your progress and offers suggestions on what to do next. Provides a review section for each topic and then practice questions. There is only one set of practice questions for each topic and they can not be repeated.
SAT test prep only. Required minimum information for registration. Has 60 lessons for math, reading, and writing. Users can select random questions, customized, or mark questions for review. Also includes two practice exams.
SAT and ACT practice questions. Provides a quiz for each section. Users can view a video explanation for each question they get wrong. Also provides flashcards.
Free Test Prep for the SAT on ProProfs
SAT test prep only. No registration required for access to study guides. Includes practice questions, articles, and flashcards. Two practice tests available. Not very organized, lots of ads.
Makers of the SAT. Offers free question of the day, sample practice questions, and one free full-length office practice test.
Makers of the ACT provides practice questions for each test section. Users can also download a PDF with practice questions for preparing for the ACT and test tips.