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.

Silicon Valley Dictionary - Urban dictionary meets Silicon Valley

Mondly - Learn 33 languages in 500 bite-size lessons and 14 conversational modules.

Reverse Dictionary - Describe a concept and get back a list of words

MondlyAR - Learn languages in augmented reality

Dictionary Anywhere - Dictionary Anywhere is an open-source and easy-to-use browser extension for Mozilla Firefox and Google Chrome that allows you to check definitions easily while browsing the web.