KeystoneJS is an open-source framework for developing database-driven websites, applications, and APIs. Built on Node.js, it leverages JavaScript and provides an easy-to-use interface for managing website content and data. KeystoneJS is known for its flexible content modeling features and seamlessly integrates with databases like MongoDB and PostgreSQL. The framework includes a powerful GraphQL API out of the box, facilitating straightforward data querying and manipulation. Its modular architecture and customizable features make KeystoneJS suitable for both simple projects and complex applications.