REST API

REST APIs are the most common type of API used in web applications. They use familiar HTTP methods to perform operations: GET to read data, POST to create data, PUT to update data, and DELETE to remove data. Each resource in the application, such as users, products, or orders, has its own URL endpoint, and clients interact with those endpoints using standard HTTP requests.

When AI tools generate backend code for vibecoded applications, they typically produce REST APIs. The AI creates routes, controllers, and data models that follow REST conventions. However, the generated APIs may have issues like inconsistent error handling, missing validation, incorrect HTTP status codes, or endpoints that expose more data than they should.

Testing REST APIs is crucial because the frontend depends on them to function. If an API endpoint returns data in an unexpected format, is slow to respond, or fails under certain conditions, the user-facing application breaks. Human QA testers discover API issues indirectly by using the application and encountering the resulting frontend failures.