A Cloudant developer works with IBM's distributed database service, Cloudant, designed for web and mobile apps. They primarily focus on creating, managing, and optimizing NoSQL databases on the cloud. Their tasks include data replication, indexing for fast data retrieval, and ensuring data durability and availability. They work with JSON documents using a flexible, schema-less data model, allowing for rapid and iterative development. They also implement data security and privacy measures. Moreover, they use Cloudant's built-in full-text search powered by Apache Lucene and complex querying with MapReduce, providing robust data analytics capabilities for applications.