Mokkup - Create Stunning Dashboard Mocks in Minutes!

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.

Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.

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

MockFlow - A super easy wireframing tool with all the other tools you need in the product design process

Lingvist - Lingvist helps you take your foreign language skills to the next level with a broad selection of exercises and lessons.