What is a REST API in Spring Boot?
Updated 2026-07-10 · Beginner friendly
Quick answer
A REST API is a way for clients to interact with your application over HTTP using standard methods on resources. In Spring Boot you build one with a RestController, mapping URLs to methods with GetMapping, PostMapping, and similar. GET reads data, POST creates, PUT updates, and DELETE removes, and responses are usually JSON.
The HTTP methods to resources
- GET: read a resource.
- POST: create a new resource.
- PUT: update an existing resource.
- DELETE: remove a resource.
@RestController
@RequestMapping("/users")
class UserController {
@GetMapping("/{id}")
User get(@PathVariable int id) { return service.find(id); }
@PostMapping
User create(@RequestBody User u) { return service.save(u); }
}In the interview
Mention PathVariable for values in the URL and RequestBody for data in the request body. Knowing which annotation reads which part of the request shows you can actually build endpoints, not just describe REST.
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