The dominant flashcard platform, now powered by generative AI. Key 2025 features include 'Magic Notes' (turning lecture notes into study sets instantly) and 'Q-Chat' (a Socratic AI tutor). While its library of 700M+ sets is unmatched, the strict paywalling of legacy study modes and aggressive annual billing have sparked a search for free, AI-native alternatives.

The world's largest course marketplace, currently being absorbed into the Coursera ecosystem (announced Dec 2025). While it offers 210,000+ courses, it has faced criticism for a 'subscription-first' pivot that de-prioritizes individual purchases and significantly reduces instructor payouts. In 2025, it integrated 'Udemy Intelligent' AI to help students find learning paths and summarize transcripts.