MongoDB query documents are quite powerful. This brings part of that usefulsness to PostgreSQL by letting you query in a similar way. This tool converts a Mongo query to a PostgreSQL "where" clause for data stored in a jsonb field. It also has additional converters for Mongo projections which are like "select" clauses and for update queries. The goal of this is to eventually provide an adapter which lets Postgres serve as a drop in replacement for Mongo, but that is not there yet. Currently the project has many of the underlying conversions that will be required to do this. For that project, see pgmongo.