HTTP Status Codes: Website & Server Guide for SEO

Website & Server Status Codes: Meaning and Importance

When you visit a website, your browser communicates with a web server behind the scenes. During this communication, the server responds with a status code—a three-digit number that indicates whether the request was successful or not. Understanding these status codes is crucial for website maintenance, user experience, and SEO. They help you identify errors, maintain proper redirects, and ensure search engines can index your site correctly.

What Are HTTP Status Codes?

HTTP status codes are three-digit numbers returned by a web server in response to a browser or client request. They indicate how the server handled the request and guide both users and search engines in understanding the state of the page.

HTTP Status Code Categories

HTTP status codes are grouped into five major categories, each indicating a different type of response:

🔵 1xx Informational (100–199): These codes indicate that the request has been received and that the server is continuing to process it. They are mainly used for informational purposes during the request and response process.

🟢 2xx Success (200–299): Success codes indicate that the request was successfully processed by the server. The most common is 200 OK, which means the requested page is available and working as intended.

🟡 3xx Redirection (300–399): Redirection codes show that further action is required to complete the request. Typically, this means the client needs to follow a different URL to access the requested resource, such as with a 301 Moved Permanently or 302 Found redirect.

🔴 4xx Client Error (400–499): Client error codes indicate that the request could not be completed due to an issue on the client side. Common examples include 404 Not Found for missing pages or 403 Forbidden for restricted access. These errors can negatively impact user experience and SEO.

⚫ 5xx Server Error (500–599): Server error codes signify that the server failed to fulfill a valid request. Examples include 500 Internal Server Error, 502 Bad Gateway, and 503 Service Unavailable. These errors require immediate attention to ensure both users and search engines can access the site.

Common HTTP Status Codes (and What They Mean)

200 OK

Meaning: The request has succeeded.
SEO Impact: Ideal. This is what you want most pages to return.

301 Moved Permanently

Meaning: The requested page has been permanently moved to a new URL.
SEO Tip: Use this when permanently redirecting old pages to new ones. It helps transfer SEO value.

302 Found (Temporary Redirect)

Meaning: The resource temporarily resides under a different URL.
SEO Tip: Use only for temporary moves. Avoid for long-term redirects.

403 Forbidden

Meaning: The server understands the request but refuses to authorize it.
Common Causes: Incorrect permissions, blocked IPs, or misconfigured .htaccess rules.

404 Not Found

Meaning: The server can’t find the requested page.
SEO Tip: Too many 404 errors can hurt user experience and SEO. Fix broken links or redirect deleted pages.

500 Internal Server Error

Meaning: A generic server error occurred.
Common Causes: Misconfigured files, plugin conflicts, or server overload.
SEO Tip: Fix immediately—search engines may de-index broken pages.

503 Service Unavailable

Meaning: The server is temporarily unable to handle the request.
SEO Tip: Use this if the site is under maintenance. It signals to search engines that the issue is temporary.

🔵 1xx – Informational Responses

100 Continue – The server received the request headers, the client should proceed.
101 Switching Protocols – The server is changing protocols as requested.
102 Processing – The server is processing the request (WebDAV).
103 Early Hints – Preload resources while preparing the final response.

🟢 2xx – Success Codes

200 OK – Standard success response.
201 Created – A new resource has been created.
202 Accepted – Request accepted, processing pending.
203 Non-Authoritative Information – Modified response from a proxy.
204 No Content – Success, but no content returned.
205 Reset Content – Reset the document view.
206 Partial Content – Partial response for range requests.

🟡 3xx – Redirection Codes

300 Multiple Choices – Multiple options available.
301 Moved Permanently – URL has permanently changed.
302 Found – Temporary redirect.
303 See Other – Use GET method to access another resource.
304 Not Modified – Cached content not changed.
305 Use Proxy – Use proxy server to access.
307 Temporary Redirect – Temporary redirect, method unchanged.
308 Permanent Redirect – Permanent redirect, method unchanged.

🔴 4xx – Client Error Codes

400 Bad Request – Invalid syntax.
401 Unauthorized – Requires authentication.
402 Payment Required – Reserved for future use.
403 Forbidden – Access denied.
404 Not Found – Resource not found.
405 Method Not Allowed – HTTP method not allowed.
406 Not Acceptable – Unacceptable response format.
407 Proxy Authentication Required – Proxy login needed.
408 Request Timeout – Client took too long.
409 Conflict – Conflict with current state.
410 Gone – Permanently removed.
411 Length Required – Missing Content-Length header.
412 Precondition Failed – Conditions in headers not met.
413 Payload Too Large – Request body too large.
414 URI Too Long – URL is too long.
415 Unsupported Media Type – Format not supported.
416 Range Not Satisfiable – Cannot return requested byte range.
417 Expectation Failed – Expectation cannot be met.
418 I'm a Teapot – Joke code (RFC 2324).
421 Misdirected Request – Sent to wrong server.
422 Unprocessable Entity – Semantic error (WebDAV).
423 Locked – Resource is locked (WebDAV).
424 Failed Dependency – Failed due to previous error (WebDAV).
425 Too Early – Request made too soon.
426 Upgrade Required – Client must upgrade protocol.
428 Precondition Required – Server requires a precondition header.
429 Too Many Requests – Rate limit exceeded.
431 Request Header Fields Too Large – Headers are too large.
451 Unavailable For Legal Reasons – Content blocked due to legal reasons.

⚫ 5xx – Server Error Codes

500 Internal Server Error – Generic server error.
501 Not Implemented – Functionality not supported.
502 Bad Gateway – Invalid response from upstream server.
503 Service Unavailable – Server temporarily overloaded or under maintenance.
504 Gateway Timeout – Server didn’t respond in time.
505 HTTP Version Not Supported – Unsupported HTTP version.
506 Variant Also Negotiates – Error in content negotiation.
507 Insufficient Storage – Not enough storage (WebDAV).
508 Loop Detected – Infinite loop detected (WebDAV).
510 Not Extended – Additional extensions needed.
511 Network Authentication Required – Network login required.

Why Status Codes Matter for SEO

Search engine crawlers use status codes to understand the site’s structure.

Broken pages (404) and server errors (5xx) can hurt SEO rankings.
Proper redirects (301) help preserve link equity and ensure a smooth user experience.

How to Check Website’s Status Codes

You can check status codes using:

Browser Dev Tools (Network tab)
Online tools like httpstatus.io
SEO software such as Screaming Frog or Ahrefs
Server logs from the hosting provider

Conclusion

Understanding HTTP status codes is essential for maintaining a healthy website, improving user experience, and optimizing SEO performance. Each category—from informational 1xx codes to server-side 5xx errors—provides valuable insight into how your site communicates with browsers and search engines. Properly handling these codes ensures that users can access content smoothly, search engines can crawl and index pages efficiently, and issues like broken links, improper redirects, or server failures are minimized. Regularly monitoring and addressing status codes helps prevent traffic loss, enhances site reliability, and supports long-term search engine visibility. By implementing best practices for redirects, fixing client and server errors, and ensuring successful responses for all critical pages, website owners can maintain a robust, accessible, and search-engine-friendly website.