CouchDB is an open source, document-oriented NoSQL database. It is a distributed database system that stores data in JSON-like documents and can be accessed using a web browser. CouchDB is designed to store, query, and aggregate data for web applications; it is not a relational database and does not support SQL. The data stored in CouchDB is highly available and can be replicated across multiple servers for scalability and failover. CouchDB is highly scalable and provides a number of features that make it suitable for large-scale applications. It supports an extensive set of features including transactions, authentication, and replication. Additionally, CouchDB is designed to be highly reliable and fault-tolerant. It is also designed to be easy to use and administer, and supports a wide range of programming languages and tools.
CouchDB is not linked to the _relational_DB model: it is "NoSQL". ... Any _database could be an alternative, but a relational database like MySQL cannot be a good alternative to a "NoSQL" database.
SQLite is relational and CouchDB is "NoSQL".