Anki is powerful but the UI is intimidating. Duolingo is fun but gives you no control over content. Flipo merges both: spaced repetition with full card control, but with XP, streaks, weekly leagues and an animated mascot (Flip) that turn studying into a habit.
The app is offline-first. LocalStorage is the source of truth and server sync is eventual. You can study without internet and data syncs when the connection comes back, even across tabs via BroadcastChannel.
The repetition algorithm uses FSRS-5 (state of the art) with SM-2 as fallback. Imports Anki .apkg decks with a custom parser. Rich text editor with cloze, images and audio. Study sessions with animated 3D flip, visual feedback and XP summary.
Full gamification: weekly leagues (Bronze to Obsidian) with promotion and demotion, unlockable achievements, hearts/lives, and a dashboard with streak, daily goal, pending cards and GitHub-style activity calendar.