Polymorphism is a crucial concept in API development, enabling the use of a single endpoint to handle similar but distinct objects, thereby streamlining API design and reducing endpoint duplication. The article illustrates this using a real estate agency application, where a single endpoint can process both house and apartment data by identifying shared and unique attributes within each accommodation type. JSON Schema's combinators like `anyOf` and `oneOf` support this approach by allowing the inclusion of varied schemas, while the discriminator keyword in OpenAPI and AsyncAPI helps distinguish between object types based on specific properties. This method not only simplifies API consumption but also aligns with the Single Source of Truth and Don’t Repeat Yourself principles, thereby enhancing maintainability and scalability. The documentation emphasizes the importance of clear API documentation, as demonstrated through Bump.sh, to ensure that consumers are well-informed about the polymorphic nature of APIs.