APIMatic's Code Generation Engine transforms input API description files into a standardized format, validates and corrects them, generates client libraries, and includes documentation and packaging options. The engine follows a five-step process: transformation, validation and correction, SDK generation, documentation generation, and packaging. It allows API providers to customize code generation using simple settings, and the generated SDKs come with utility classes, authentication helpers, and configuration files, providing strict language bindings and SOLID software design principles. While automatic SDK generation offers benefits such as increased API adoption and cost savings, there are scenarios where manual SDK writing might be more suitable, depending on specific business logic requirements.