So you've finished all of Magoosh SAT's practice questions and tests. Way to go! You've just put a lot of test prep under your belt.
To be even more prepared, there are a few other places you can go for good SAT practice tests that will prepare you for the real exam on test day.
The very best non-Magoosh SAT practice exams are the "real" practice exams-- the official practice SATs from the College Board. The College Board is the company that makes the SAT you'll see on test day.
The bad news is that there are relatively few official SAT Practice tests-- only four of them. The good news is that the four official SAT practice tests can be accessed online for free. There's also more good news: the College Board provides additional official SAT practice questions (but not whole exams) through their free Daily Practice app. For detailed instructions on how to access the official practice tests and app, see Chris Lele's blog post on where to find full-length SAT practice tests.
Once you get beyond Magoosh and College Board practice tests, other "unofficial" sources for practice SAT exams are hit and miss. Many third-party SAT practice companies simply fail to make good, truly SAT-like practice exams. Still, one unofficial SAT prep provider has been pretty strong in recent years: Barron's. So consider Barron's SAT as an additional non-Magoosh source of SAT practice exams.