It’s easy for user to migrate from MongoDB to YugaByte.
CosmosDB is a successful instance.
Hi @ychtiger
A MongoDB compatible driver is not in the current plans. Maybe sometime in the future 
Our approach to support flexible schema is via native support for JSON data type in YCQL (our Cassandra compatible API). In addition to columns of primitive types, tables in YugaByte can have one or more JSONB columns as well.
Is that something that’ll work for you?
regards,
Kannan