Glossary: Spring Boot Beyond the Basics

HTTP status codes

Also written: 201, 400, 401, 403, 404, 409, 201 Created, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 409 Conflict, 502, 503

Three-digit numbers a server sends to say how a request went. Common ones in an API like Kettle & Crane's are 201 Created (something was saved), 400 Bad Request (invalid input), 401 Unauthorized (no or wrong login, so the server doesn't know who you are), 403 Forbidden (known user without the needed role), 404 Not Found (no such item), 409 Conflict (a clash with current data, such as a stale `@Version`, a taken email or too little stock), and 502/503 for a failing or unavailable remote service.