Testing API endpoints of a complex microservice application without a front-end typically involves a combination of manual and automated testing approaches. Here's a step-by-step guide on how to approach this: Understand the API Documentation: Begin by thoroughly studying the API documentation. Understand the available endpoints, request methods (GET, POST, PUT, DELETE, etc.), request headers, request parameters, and response formats. Set Up an Isolated Test Environment: Create a dedicated testing environment that mirrors the production environment as closely as possible. This includes setting up the microservices, databases, and any other dependencies that your APIs rely on. Manual Testing: Start with manual testing to validate basic functionality and gather initial feedback. Use tools like Postman, curl, or any API testing tool of your choice to send requests and examine responses. Test different scenarios, including edge cases, and ensure that error responses are handled gracef...