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.
MailMate - MailMate is an alternative email client that was designed for the macOS.
Kanshudo - Master kanji, hiragana and katakana, along with Japanese grammar and vocabulary.
Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
EarthFluent - Learn languages for Free!
Airmail - Airmail is a lightweight and lightning fast mail client for Mac.