Kazumi
Flutter-based, rule-driven anime collection
...The app supports streaming with real-time super resolution (via Anime4K), danmaku (on-screen comments), multiple video sources, offline caching, and even collaborative watching modes. It targets many platforms (Android, iOS, Windows, macOS, Linux) and supports custom rule importing and sharing. The interface includes features like search, schedule, history, subtitles, and rule editing. It is actively developed (as of the repository) and licensed under GPL-3.0.