Duolingo
Duolingo is a language-learning platform available as a mobile app and web-based tool.
It offers courses in 40 languages, including some smaller language varieties and conlangs.
Duolingo is a versatile platform that utilizes gamification to enhance the process of learning new languages.
It is transitioning some courses (Spanish, French, German) to the standards set by the Common European Framework of Reference for Languages (CEFR), providing structured progression for improving essential language skills, which include speaking, listening, and writing.