NoER: A Tool for End-to-End Design of Document Databases

Database design is a crucial practice in relational databases, following well-established patterns. The rising popularity of document-oriented NoSQL databases has changed how data modeling is perceived due to their flexible schema. As a consequence, data modeling is often reduced to an application-driven approach, where conceptual design is not addressed and schema decisions are tightly coupled with implementation details. Recent work has shown that Entity-Relationship (ER) modeling principles can be adapted to design document schemas, but practical tool support remains limited. We present NoER, a web-based system that supports a conceptually grounded and guided design process for document-oriented databases using a revised version of the ER model. It guides users through an end-to-end workflow, from conceptual schema definition to the interactive exploration of translation alternatives and the automatic generation of a MongoDB-compatible JSON schema. The demonstration showcases how NoER helps users compare design options, apply document design patterns consistently, and derive document schemas that are aligned with application requirements and easier to maintain.