Rest API Basics

CORS (Cross-Origin Resource Sharing) errors are one of the most persistent and confusing issues developers face when integrating modern frontend frameworks like Angular and React with a Spring Boot backend. You may see errors such as: Or: These are not Spring errors — they’re browser security mechanisms rejecting your call because it violates same-origin policy. […]

Understanding the full request lifecycle in Spring Boot—from the moment a client makes an HTTP request to the moment a response is sent—is one of the most powerful frameworks concepts you can master. Most developers learn controllers and services, but not the plumbing that makes REST APIs work reliably in real systems. This guide walks

REST APIs are the backbone of modern web and microservice architectures.Spring Boot makes building REST APIs straightforward, but to use them in real systems, you must understand not just what to annotate — but why and how it works end-to-end. This guide explains REST APIs in Spring Boot with production-grade clarity, covering request routing, status