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.
GrowthList - A crowd-sourced list of growth hacks
Mondly - Learn 33 languages in 500 bite-size lessons and 14 conversational modules.
GrowthHackers Projects - Growth collaboration software for teams 📈
MondlyAR - Learn languages in augmented reality
Marketing Examples - A gallery of real world marketing case studies. Updated every day.