Designing and developing a web application involves breaking down the idea into parts, including a backend API layer, client-facing UI layer, and data layer. The data layer uses a NoSQL database like Couchbase to store and manage data, which can be queried using SQL or key-value operations. The Java SDK for Couchbase provides a convenient way to interact with the database, allowing developers to create RESTful APIs that serve JSON data. The backend API layer serves as a bridge between the data and UI layers, while the client-facing UI layer provides a user-friendly interface. To develop the application, developers can focus on creating endpoints that perform different queries or lookups against Couchbase, using options like Spring Boot for simplicity.