A CouchDB developer is responsible for designing, implementing, and managing databases using CouchDB, an open-source NoSQL database. They create scalable and high-performance applications that can handle large amounts of data. Tasks include data modeling, schema design, and query optimization. They are also responsible for ensuring data consistency, reliability, and security. Furthermore, they troubleshoot any issues that arise and provide maintenance. Often, they work closely with other developers, integrating CouchDB into various applications and services. They also need to stay updated with the latest advancements in CouchDB and other similar technologies to enhance application performance.