Duolingo

Duolingo teaches 40+ languages through short, gamified lessons designed to make daily practice habit-forming, with AI personalizing difficulty and review timing based on what you're actually forgetting. Duolingo Max adds GPT-powered conversation practice and explanations, and the company made real waves in 2025 by going 'AI-first' — cutting contractor roles, including translators and content writers, in favor of AI-generated content, a decision that drew significant public backlash even as the company leaned further into it.