Every time a user clicks a link, types a URL, or loads a page, the browser and server exchange signals. These signals are called HTTP or HTTPS status codes. They are short numbers that explain what is happening with a request.
For developers, status codes are essential for debugging and server management. For SEOs, they are equally important because they influence how search engines crawl, index, and rank websites. A single wrong status code can block Googlebot from seeing your page or can waste your crawl budget.
HTTPS is the secure version of HTTP, but both use the same set of status codes. Whether your site runs on HTTP or HTTPS, the meaning and SEO effect of each code remains the same.
Checking your site’s HTTP status codes is a crucial step in any technical SEO audit. By monitoring and fixing them, you improve crawl efficiency, maintain indexation, and protect user experience.
What Are HTTP Status Codes?
HTTP status codes are three-digit numbers returned by a server when a browser or search engine makes a request. They act as a communication system that explains whether the request was successful, redirected, failed, or encountered an error.
The Five Classes of Status Codes
- 1xx Informational: Request received and continuing process
- 2xx Success: Request successful and the content is delivered
- 3xx Redirection: The request is redirected to another resource
- 4xx Client Error: The request is invalid or the resource cannot be found
- 5xx Server Error: The server failed to fulfill a valid request
The Five Classes of Status Codes
1xx Informational
These codes confirm that a request is being processed. They are rarely seen by users and have minimal SEO impact.
2xx Success
These codes show that a request was successful and the server delivered the content.
3xx Redirection
Redirection codes tell browsers and crawlers that the requested content has moved. Choosing the right redirection type is critical for SEO.
4xx Client Error
Client error codes indicate that the request was invalid or could not be fulfilled. Too many 4xx errors can harm user experience and crawl efficiency.
5xx Server Error
These codes mean that the server could not respond correctly. Frequent 5xx errors can prevent crawling and lead to ranking issues.
Full HTTP Status Code Cheat Sheet (with SEO Notes & Fixes)
Unlike many basic lists, this guide connects each code with SEO effects and practical fixes.
| Code | Meaning | SEO Impact | Fix or Best Practice |
| 200 | OK | Ideal for indexable pages | Use for canonical pages |
| 201 | Created | Rare in SEO, mainly API | Ensure proper indexing only if content must be public |
| 204 | No Content | Valid but not visible in search | Use for tracking pixels or empty responses |
| 301 | Permanent Redirect | Passes link equity | Use for migrations and avoid redirect chains |
| 302 | Temporary Redirect | Does not always pass equity | Use only for temporary moves |
| 304 | Not Modified | Saves crawl budget | Correct when content unchanged |
| 307 | Temporary Redirect (HTTP/1.1) | Treated like 302 | Use for short-term testing |
| 308 | Permanent Redirect (HTTP/2+) | Passes equity | Use instead of 301 in advanced setups |
| 400 | Bad Request | Page inaccessible | Check request syntax |
| 403 | Forbidden | Blocked access | Review permissions and server rules |
| 404 | Not Found | Hurts crawl if excessive | Redirect useful URLs, keep genuine 404s for useless pages |
| 410 | Gone | Signals permanent removal | Use when content should be deindexed |
| 429 | Too Many Requests | Crawl delay issues | Add Retry-After and optimize server load |
| 451 | Unavailable for Legal Reasons | Rare, limited SEO use | Required for compliance cases |
| 500 | Internal Server Error | Stops indexing | Fix server scripts and logs |
| 502 | Bad Gateway | Proxy error | Check CDN or hosting provider |
| 503 | Service Unavailable | Temporary outage | Use with Retry-After header during maintenance |
| 504 | Gateway Timeout | Server too slow | Upgrade hosting or optimize backend |
Informational Codes (1xx)
These codes (100, 101, 102, 103) indicate that the request is in progress. For SEO, they are rarely relevant but may appear in server logs.
Success Codes (2xx)
- 200 OK: The best status code for content that should be indexed.
- 201 Created: Used after POST requests or API calls, rarely SEO related.
- 204 No Content: Valid but invisible in search results.
Redirection Codes (3xx)
- 301 Permanent Redirect: Best practice for migrations and consolidations. Passes most link equity.
- 302 Temporary Redirect: Do not use it for site migrations. Safe for testing.
- 307 and 308: More modern versions of 302 and 301. Use when working with HTTP/2.
- 304 Not Modified: Tell crawlers the page has not changed. Helps save crawl budget.
Client Error Codes (4xx)
- 400 Bad Requests: Often due to malformed URLs. Fix parameters or encoding.
- 403 Forbidden: Check server permissions. Can block crawlers if misconfigured.
- 404 Not Found: Common error. Use redirects for valuable content. Avoid serving 200 on error pages to prevent soft 404s.
- 410 Gone: Preferred when permanently removing pages you want deindexed.
- 429 Too Many Requests: Crawlers may slow down. Use Retry-After header.
- 451 Legal Restrictions: Rare but shows intentional blocking.
Server Error Codes (5xx)
- 500 Internal Server Error: A generic failure. Needs urgent fix.
- 502 Bad Gateway: Hosting or proxy issue. Contact provider.
- 503 Service Unavailable: Correct for maintenance, but add Retry-After header.
- 504 Gateway Timeout: Server too slow. Optimize performance or hosting.
Search engines treat 5xx errors as serious issues. Repeated errors can remove pages from the index.
Special and Platform-Specific Codes
Cloudflare Errors (520, 522, 525, 526, 527)
These are Cloudflare-specific and not official. They show network, SSL, or handshake errors. Always check origin server logs in parallel.
Nginx 499 Error
This means the client closed the request before the server responded. SEO impact is minimal but can waste crawl budget if frequent.
How to Check Status Codes
- Chrome DevTools: Open Network tab, reload page, check response.
- curl -I command: Quick way to test from terminal.
- Google Search Console: Coverage report lists status issues.
- SEO Crawlers: Use Screaming Frog, Sitebulb, or ClickRank to scan at scale.
- Server Logs: Best source for detailed tracking.
Best Practices for SEO and Technical Health
- Always serve 200 for canonical, indexable content.
- Use 301 for permanent redirects and avoid chains.
- Apply 410 for permanent removals you want deindexed.
- Serve 503 with Retry-After during planned downtime.
- Monitor 5xx errors closely and fix hosting instability.
- Use 304 responses to save crawl budget when content is unchanged.
When updating metadata after resolving status issues, the Free AI Meta Description Generator can help create SEO-friendly descriptions faster.
Common SEO Mistakes with Status Codes
- Serving 200 on error pages, leading to soft 404s.
- Using 302 instead of 301 during migrations.
- Creating redirect loops or chains.
- Overusing 404s instead of consolidating content with redirects.
Conclusion
HTTPs status codes are the backbone of web communication. They guide browsers, users, and search engines on what to do next. For SEO, choosing the right code can make the difference between efficient crawling and wasted resources.
Regularly reviewing and fixing status codes should be part of every technical SEO workflow. With the right setup, you ensure that search engines crawl only what matters, index your important pages, and users get a smooth experience.
What are the five classes of HTTP status codes?
They are informational (1xx), success (2xx), redirection (3xx), client error (4xx), and server error (5xx).
What is the difference between 301 and 302 redirects?
301 is permanent and passes link equity. 302 is temporary and should only be used for short-term moves.
What is a soft 404 and how do I fix it?
A soft 404 happens when a page shows an error but returns a 200 status. Fix by serving a real 404 or redirecting to a relevant page.
What does 304 Not Modified mean in SEO?
It tells crawlers the page content has not changed. This saves crawl budget.
Which status code should I use for maintenance mode?
Use 503 Service Unavailable and include a Retry-After header.
Why am I seeing 5xx errors on my site?
These mean your server cannot handle requests. Fix server configuration, hosting, or backend scripts.
What is status code 499 in Nginx?
It means the client closed the connection before the server responded.
