non-relational, document oriented pubsub architecture based on MongoDB, good for not much more than chat apps. For toy apps (in 2012-2016) – use firebase (also for chat apps), for crud-spectrum and enterprise apps - use sql. And then React happened and consumed the entire spectrum of frontend architectures, bringing us to GraphQL, which didn't, but the hype wave left little oxygen remaining for anything else. (Even if it had, still Meteor was not better.)