HTTP Status Code Lookup
Look up any HTTP status code — see its meaning, category, and when it's used. Search by code number or name.
24 codes found
Informational
The server has received the request headers; the client should proceed to send the request body.
The server is switching protocols as requested by the client (e.g., to WebSocket).
Success
The request was successful. The response body contains the requested data.
The request was successful and a new resource was created.
The server processed the request but returns no body content.
Redirection
The resource has moved to a new URL permanently. Update your links.
The resource is temporarily at a different URL. Keep using the original URL.
The resource hasn't changed since last request. Use your cached version.
Temporary redirect preserving the HTTP method of the original request.
Permanent redirect preserving the HTTP method of the original request.
Client Error
The server cannot process the request due to malformed syntax or invalid parameters.
Authentication is required. The request lacks valid credentials.
The server understood the request but refuses to authorise it.
The requested resource could not be found on the server.
The HTTP method used is not supported for this resource.
The request conflicts with the current state of the resource.
The resource is permanently gone and will not return.
The request body exceeds the server's size limit.
The request is well-formed but contains semantic errors.
You have sent too many requests in a given time. Slow down.
Server Error
The server encountered an unexpected condition.
The server received an invalid response from an upstream server.
The server is temporarily unable to handle the request (overload or maintenance).
The upstream server failed to respond in time.
HTTP Status Codes: The Language of the Web
Every time your browser loads a page, an API returns data, or a form submits, the server sends back a three-digit number. That number tells the client exactly what happened — did the request succeed? Did the resource move? Is the server broken? HTTP status codes are the universal language servers use to communicate results.
You don't need to memorise all of them — there are about 60 defined codes — but knowing the major ones saves hours of debugging. When your API returns a 422 instead of a 400, or a 301 instead of a 302, the difference matters. It affects how browsers cache, how search engines index, and how your users experience errors.
This reference covers every status code you'll actually encounter. Search by number, name, or description to find exactly what you need.
Status Code Categories at a Glance
| Range | Category | Meaning | Common Examples |
|---|---|---|---|
| 100-199 | Informational | Request received, continuing process | 100 Continue, 101 Switching Protocols |
| 200-299 | Success | Request received, understood, and accepted | 200 OK, 201 Created, 204 No Content |
| 300-399 | Redirection | Further action needed to complete request | 301 Moved, 302 Found, 304 Not Modified |
| 400-499 | Client Error | Request contains an error from the client side | 400 Bad Request, 401 Unauthorized, 404 Not Found |
| 500-599 | Server Error | Server failed to fulfil a valid request | 500 Internal Error, 502 Bad Gateway, 503 Unavailable |
What this means for you: If you're debugging an issue, the first digit tells you where to look. 4xx = your request has a problem (check your code). 5xx = the server has a problem (check logs or wait for the service to recover).
The Status Codes That Trip People Up
401 vs 403
401 means "I don't know who you are" — send credentials. 403 means "I know who you are, but you're not allowed." The fix for 401 is authentication. The fix for 403 is authorisation (different permissions).
301 vs 302 vs 307
301 is permanent (search engines transfer SEO value). 302 is temporary (keep indexing the original URL). 307 is like 302 but guarantees the HTTP method doesn't change — critical for POST requests that shouldn't become GETs.
400 vs 422
400 means the request is malformed — bad JSON, missing required headers. 422 means the request is valid but the data doesn't make sense — like submitting a form with an email field containing "not-an-email". Use 422 for validation errors.
502 vs 503 vs 504
502 means a proxy/gateway got a bad response from the upstream server. 503 means the server is overloaded or in maintenance. 504 means the upstream server didn't respond in time. All three mean "try again later," but the root cause differs.
SEO Impact of Status Codes
| Code | SEO Effect | Best Practice |
|---|---|---|
| 200 | Page indexed normally | Return for all valid, indexable pages |
| 301 | SEO value transfers to new URL (90-99%) | Use for permanent URL changes, domain migrations |
| 302 | SEO value stays on original URL | Use for A/B tests, temporary maintenance pages |
| 404 | Page removed from index after crawls | Set up a custom 404 page, fix broken links |
| 410 | Removed from index faster than 404 | Use when content is permanently, deliberately removed |
| 503 | Tells crawlers to come back later | Use during planned maintenance (not for blocking bots) |
What this means for you: Using the wrong redirect code can cost you search rankings. A 302 when you meant 301 means Google keeps indexing the old URL. A 404 when you should use 301 means you lose the link equity the old page had built up.
API Design: Choosing the Right Code
| Scenario | Code | Why Not Something Else |
|---|---|---|
| Successful creation (POST) | 201 Created | 200 works but 201 is more specific — include a Location header |
| Successful delete | 204 No Content | 200 with an empty body is confusing — 204 is unambiguous |
| Invalid form data | 422 Unprocessable | 400 means the request itself is broken (bad JSON), not the data |
| Resource already exists | 409 Conflict | More descriptive than 400 — tells the client to resolve the conflict |
| Rate limited | 429 Too Many Requests | Include a Retry-After header so clients know when to try again |
Related Tools
How to use this tool
Type a status code number or keyword in the search box
Browse results grouped by category (success, redirect, error)
Read the description to understand when and why each code is used
Common uses
- Looking up unfamiliar HTTP error codes during debugging
- Choosing the correct status code for REST API responses
- Understanding redirect types for SEO configuration
- Diagnosing server errors from monitoring alerts
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