Jisho is a powerful Japanese-English dictionary. It lets you find words, kanji, example sentences and more quickly and easily.
Enter any Japanese text or English word in the search box and Jisho will search a myriad of data for you. You can enter an entire sentence in Japanese or even perform a multi-word search with a mix of English and Japanese. If you enter longer Japanese text each word and particle will be segregated, furigana will be added and if you click on any of them you will get detailed information without needing to refresh the page.
Another cool feature is that you can search for groups of words by JLPT level (e.g., #jlpt-n3 #adjective will show all 458 adjectives that belong to the JLPT N3 level). You can do the same for kanji by grade level.
Finally, you can search by radical or input via handwriting.
Editor’s Note: this is by far one of the best online dictionaries available but unfortunately there is no mobile app for it.