PolyglotGym is a free language gym: structured CEFR courses (A1-C2) with interactive exercises, grammar guides, spaced-repetition vocabulary, dialect comparisons, and native-quality audio for 100+ languages - including ones no big app teaches: Icelandic, Georgian, Belarusian, Mongolian, Tagalog, Luxembourgish. Explanations adapt to your native language instead of being translated, and courses are free without signup. Web, iOS, and Android.