Complete HTTP Status Codes Reference for REST API Devs

HTTP status codes are the contract language of APIs. When your frontend receives a response, the status code is the first signal: did it work, where did it go, what went wrong? A good API uses status codes precisely; a confusing API returns 200 OK with "error": true in the body. This reference covers every status code you'll encounter in REST API development—with the context, examples, and gotchas that actually matter. Use the DevPlaybook HTTP Status Codes Tool to look up any code quickly. Status Code Categories Range Category Your API Should... 1xx Informational Rarely return these manually 2xx Success Be specific: 200 vs 201 vs 204 3xx Redirection Use 301/308 for permanent, 302/307 for temporary 4xx Client Error Be descriptive: explain what the client did wrong 5xx Server Error Never expose internals; log details server-side 1xx — Informational Informational codes are protocol-level responses that indicate the server received the request and is processing it. REST APIs rarely return