zkanji - zkanji is a free and open-source study tool and dictionary of the Japanese language.
WaniKani - Learn around 1,700 kanji and 5,000 vocabulary words in about a one to two years.
RomajiDesu - RomajiDesu is a free online bi-directional Japanese-English dictionary, Kanji dictionary, Sentence analyzer and Japanese to Romaji/English translator, and Romaji to Hiragana/Katakana Converters for Japanese learners.
Kanji Koohii - Remember the kanji; mnemonics, smart dictionary, flashcards, spaced repetition.
Jisho - Powerful and easy-to-use online Japanese-English dictionary with words, kanji and example...
Kanshudo - Master kanji, hiragana and katakana, along with Japanese grammar and vocabulary.