Which of the following are types of Document Database?

MongoDB is an open source, cross-platform, document-oriented database management system that uses flexible documents instead of tables and rows to process and store various forms of data. Use cases : Mobile applications, Real-time analytics, Content management systems. Cloudant is an IBM software product, which is primarily delivered as a cloud-based service. Cloudant is a non-relational, distributed database service of the same name. Cloudant is based on the Apache-backed CouchDB project and the open source BigCouch project.