After spent some months on Brilliant.org, I realized that I want to go deeper. I loved the way Brilliant teach but I think that the site (topics part) are too vague, so i'm looking for other resources like sites or book at pre-calculus level.
P.S. Math level High school.
Take a look at Khan Academy, they have very in depth courses for free, with great teachers and quizzes along the way. It's completely self paced. Also, this may be an unpopular opinion, but I've found it works well in combination with Wikipedia to get a deeper knowledge of things. And of course, here! This website is your best resource.
As for books, my personal favorite is Precalculus Mathematics in a Nutshell: Geometry, Algebra, Trigonometry by George F. Simmons. And to get an intuitive idea of calclulus, take a look at Spivak's The HitchHiker's Guide to Calculus.
Perhaps later when you want to get into calculus, Spivak's Calculus will become your bible.