LearnObit - A tool for your learning, like Anki & Workflowy in one
zkanji - zkanji is a free and open-source study tool and dictionary of the Japanese language.
Kanji Book - Learn Japanese online with kanji mnemonics. Study all of the jōyō kanji with the best spaced repetition system. It's easier and better than any flashcard app.
Jisho - Powerful and easy-to-use online Japanese-English dictionary with words, kanji and example...
Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.
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.