Judo Academy is a learning app for judo — quizzes, a 90-technique library, an AI sensei you can ask anything, and a training journal, all built around real belt progression. It started as a quiz app built for my daughter, and grew from there. Core features (technique library, daily challenges) are free and unlimited. Premium unlocks unlimited quiz/AI/journal usage for €4.99/mo. Available on Android, in 8 languages.