HTTP Status Code Comparisons
Understanding the subtle differences between similar HTTP status codes is essential for designing clean APIs and debugging network interactions.
Articles & Guides
400 Bad Request vs. 404 Not Found: Malformed Request vs. Missing Target
Understand the difference between HTTP 400 Bad Request and 404 Not Found, syntax vs routing errors, and how to avoid misclassifying API failures.
401 Unauthorized vs. 407 Proxy Authentication Required
Understand the difference between HTTP 401 Unauthorized and 407 Proxy Authentication Required, origin auth vs intermediary proxy gateways.
401 vs. 403: What Is the Difference?
Understand the practical difference between HTTP 401 Unauthorized and 403 Forbidden, why the names can be confusing, and how to verify the real cause.
405 Method Not Allowed vs. 501 Not Implemented
Understand the difference between HTTP 405 Method Not Allowed and 501 Not Implemented, endpoint-level rejection vs server-wide protocol capability.
413 Payload Too Large vs. 415 Unsupported Media Type
Understand the difference between HTTP 413 Payload Too Large and 415 Unsupported Media Type, body size limits vs payload format constraints.
500 Internal Server Error vs. 502 Bad Gateway
Understand the difference between HTTP 500 Internal Server Error and 502 Bad Gateway, origin application crashes vs reverse proxy communication failures.
GET vs. POST: Safe Methods, Caching, and Body Payloads
Understand the difference between HTTP GET and POST methods, safe and idempotent method semantics, caching behavior, and request body guidelines.
HEAD vs. GET: Inspecting Headers Without Downloading the Body
Understand the difference between HTTP HEAD and GET methods, how HEAD inspects headers and validates cache freshness without downloading the response payload.
HTTP 400 Bad Request vs 422 Unprocessable Content
Understand the difference between HTTP 400 Bad Request and 422 Unprocessable Content, syntax vs semantics, and when to use each in API design.
HTTP 403 Forbidden vs 404 Not Found for Hidden Resources
Compare HTTP 403 Forbidden and 404 Not Found when designing security and resource disclosure policies for private or hidden API endpoints.
HTTP 404 Not Found vs 204 No Content for a Missing Resource
Understand when to return HTTP 404 Not Found versus 204 No Content for missing resources, empty query results, and DELETE requests in REST APIs.
HTTP 408 Request Timeout vs 504 Gateway Timeout
Compare HTTP 408 Request Timeout and 504 Gateway Timeout, client-to-server latency vs proxy upstream timeouts, and retry safety.
HTTP 409 Conflict vs 422 for an Existing Resource
Compare HTTP 409 Conflict and 422 Unprocessable Content when handling existing resources, duplicate submissions, and state conflicts in REST APIs.
HTTP 429 Too Many Requests vs 503 Service Unavailable
Compare HTTP 429 Too Many Requests and 503 Service Unavailable, client rate limits vs server capacity, and how to handle Retry-After headers.
HTTP 502 Bad Gateway vs 504 Gateway Timeout
Understand the difference between HTTP 502 Bad Gateway and 504 Gateway Timeout, invalid responses vs timeouts, and how to debug proxy failures.
POST vs. PUT: Creation, Replacement, and Idempotency
Understand the difference between HTTP POST and PUT methods, idempotency guarantees, subordinate resource creation vs complete entity replacement.
PUT vs. PATCH: Complete Replacement vs. Partial Modification
Understand the difference between HTTP PUT and PATCH methods, complete representation replacement vs applying partial deltas with JSON Merge Patch.
Choosing the Right HTTP Status Code
When comparing HTTP status codes, consider the client versus server responsibility, request syntax versus semantics, and the exact state of the target resource.