Spring Boot Validation is a feature of the Spring Framework that allows you to validate user input in your application. Spring Boot Validation uses the Java Bean Validation API, which provides a number of built-in constraints that you can use to validate the properties of your objects.
But why API validation is essential?
API request validation is the crucial step in ensuring that client requests align with the API specifications laid out by the API developers. To avoid unexpected/wrong errors as well as slow/invalid responses, API requests should be validated first for correctness before being progressed further.