-`mastodon` this leverages [Mastodon API](https://docs.joinmastodon.org/client/intro/) and [Twitter API](https://developer.twitter.com/en/docs/twitter-api) for user login and data sync
-`catalog` manages different types of items user may review, and scrapers to fetch from external resources, see [catalog.md](catalog.md) for more details
-`journal` manages user created content(review/ratings) and lists(collection/shelf/tag), see [journal.md](journal.md) for more details
-`social` manages timeline for local users and ActivityStreams for remote servers, see [social.md](social.md) for more details
-`legacy` this is only used by instances upgraded from 0.4.x and earlier, to provide a link mapping from old urls to new ones. If your journey starts with 0.5 and later, feel free to ignore it.