A structured feature table of apps couples can use to learn a language together, covering shared vocabulary, live translation, cooperative goals and streaks, with a clear note that LinguaPair is this publisher's own product.
Published hour estimates from the US Foreign Service Institute and Cambridge English, converted into calendar timelines for 3, 5 and 10 hours a week, with a table for each CEFR level and the caveats behind every number.
A map of Duolingo alternatives arranged by goal (speaking, reading, exams) and price band, from free spaced-repetition and exchange apps to structured courses and live tutors, with a route from app-only practice to tutor-led learning.