Anki grammar deck:
https://ankiweb.net/shared/info/1846425705
All of these cards were taken from these two websites: JLPT Sensei and Pass Japanese Test. Tagged (N5 to N1). This is useful mostly after having gone through a specific textbook or sentence deck of the level that you meant to study. It serves well as review of already learned material and not to learn it from scratch. I hope it helps you all as much as it has helped me!
Genki I & II Sentence Deck (N5 and N4):
https://ankiweb.net/shared/info/2041093842
Tobira Sentence Deck (N3 and some N2):
https://ankiweb.net/shared/info/215281557
Recognition Remembering The Kanji (RRTK) Deck:
https://ankiweb.net/shared/info/1635663511
Just with all of these free materials, I have managed to reach N3 level in a few years.
PLUS, buying the Tango books (N5 through N3, about to start the N2 in the new year once the reviews from the N3 deck have gone considerably low), and getting the respective Anki deck has also helped cement vocabulary immensely.