nihongo-net.com/grammar/
Grammar pattern reference organized by JLPT level from N5 to N1, with quizzes to test understanding. Covers 495 grammar patterns for learners preparing for the JLPT.
GrammarJLPT and other testsJLPT N5JLPT N4JLPT N3JLPT N2JLPT N1Sentence patternsQuizzesJLPT