HTTP Status Codes for SEO: The Complete Reference
- April 2, 2026
- Redirects & HTTP Status Codes
Every URL a crawler touches returns an HTTP status code, and Google acts on that code. 2xx means index it, 3xx means follow the redirect, 4xx means the page is gone for the client, and 5xx (plus 429) means slow down and come back later. Permanent redirects (301, 308) pass signals and replace the old URL; temporary ones (302, 307) keep the original in the index. A 404 lingers for weeks while a 410 is dropped faster. Short-lived 503 and 429 responses are crawl-safe, but if they persist beyond a couple of days Google drops the URLs. Never use 403 or 404 to throttle Googlebot. The codes below are the ones that move SEO outcomes.
Status codes are the quiet layer of technical SEO. Visitors rarely see them, but every crawler reads them on every request, and the wrong code in the wrong place can quietly drop a page from the index or stall your crawl budget. This is the complete reference: what each SEO-relevant code means, how search engines treat it, and when it matters.
For the deep dives on the trickiest comparisons, this guide links out to the dedicated references on 301 vs 302 redirects, 404 vs 410 status codes, and 5xx server errors and SEO.
How search engines treat each class of status code
The first digit of the code tells the crawler which family it belongs to, and each family triggers a different behavior in Googlebot.
2xx: Success
A 2xx response means the request succeeded and the server returned content. Google considers 2xx pages for indexing and reads the body to decide whether the content is useful. The catch is the soft 404: a page that returns 200 but shows an error, an empty result, or a thin placeholder. Google's systems may classify these as soft 404s and treat them as missing, because the server says "success" while the page says "nothing here."
3xx: Redirection
A 3xx response tells the crawler the resource lives somewhere else. Google follows redirects and consolidates signals based on whether the redirect is permanent or temporary. Server-side redirects are the cleanest signal; long redirect chains dilute the message and waste crawl budget.
4xx: Client errors
A 4xx response means the request failed on the client side, most often because the page does not exist or is forbidden. Pages returning 4xx are not considered for indexing, and a URL that previously existed will be removed from the index. The one exception is 429, which Google treats like a 5xx.
5xx: Server errors
A 5xx response means the server failed to fulfill a valid request. Google interprets 5xx (and 429) as a temporary problem and slows its crawl rate in case the crawling itself is contributing to the load. Brief 5xx errors cost nothing in rankings; sustained ones lead to dropped URLs.
The SEO-relevant status codes, one by one
200 OK
What it means: The request succeeded and the page returned normally.
SEO impact: This is the state every indexable page should be in. Confirm that your important URLs return a genuine 200 and that error or empty pages do not return 200 by mistake, which creates soft 404s.
301 Moved Permanently
What it means: The page has permanently moved to a new URL.
SEO impact: Google transfers indexing signals to the destination and replaces the old URL in results over time. This is the default choice for permanent moves, site migrations, and consolidating duplicate URLs. See 301 vs 302 redirects for the full comparison.
302 Found
What it means: The page has temporarily moved.
SEO impact: Google keeps the original URL in the index and does not move ranking signals to the destination. Use 302 only when the move is genuinely short-term. A 302 left in place for a permanent move can delay consolidation.
304 Not Modified
What it means: The content has not changed since the crawler last fetched it, so the server returns no body.
SEO impact: This is a caching efficiency response, not a move or an error. It does not affect indexing and helps conserve crawl budget by saving bandwidth, but it is not a substitute for any redirect or removal code.
307 Temporary Redirect
What it means: A strict temporary redirect that preserves the request method.
SEO impact: Treated like a 302 for ranking purposes, with the original URL retained. One important nuance: the 307 a browser shows for HSTS is generated internally by the browser, not sent by the server. Googlebot does not see that internal HSTS 307; it follows the real underlying redirect instead.
308 Permanent Redirect
What it means: A strict permanent redirect that preserves the request method.
SEO impact: Treated like a 301, passing signals to the destination and marking it canonical. Choose 308 over 301 when the request method matters, such as form submissions or API endpoints that rely on POST, PUT, or PATCH.
401 Unauthorized
What it means: The page requires authentication that was not supplied.
SEO impact: Crawlers cannot access the content, so it will not be indexed. This is appropriate for gated areas, but make sure public pages never return 401 by accident.
403 Forbidden
What it means: The server understood the request but refuses to serve it.
SEO impact: The page will not be indexed. Critically, Google warns against using 403 (or 404) to rate-limit Googlebot, because doing so can lead to content being removed from Search. Use 503 or 429 to throttle instead.
404 Not Found
What it means: The page does not exist.
SEO impact: Not indexed, and previously indexed URLs are removed, though a 404 can linger in the index for weeks while Google waits to see if it returns. A genuine 404 for a truly missing page is correct and normal; it does not harm the rest of your site. See 404 vs 410 status codes.
410 Gone
What it means: The page existed but is intentionally and permanently removed.
SEO impact: A clearer signal than 404. Google often drops a 410 URL faster, sometimes within a single crawl cycle, because the removal is explicitly deliberate. Use 410 when you are certain the content will never come back.
429 Too Many Requests
What it means: The client is sending requests too quickly.
SEO impact: Although it is a 4xx code, Google treats 429 like a 5xx: it slows crawling rather than removing content, and it can honor a Retry-After header. This is one of the correct ways to rate-limit Googlebot. Sustained 429 responses beyond a couple of days will still cause URLs to be dropped.
500 Internal Server Error
What it means: A generic server-side failure.
SEO impact: Google slows crawling and returns later to retry. Occasional 500s are tolerated, but persistent ones reduce crawl frequency and eventually risk de-indexing. Fix the root cause rather than masking it.
502 Bad Gateway
What it means: A server acting as a gateway or proxy received an invalid response from upstream.
SEO impact: Treated as a temporary server error like other 5xx codes. Frequent 502s often point to overloaded backends or misconfigured proxies and should be resolved quickly to protect crawl rate.
503 Service Unavailable
What it means: The server is temporarily unavailable, often for maintenance or overload.
SEO impact: The crawl-safe way to signal a planned outage. A short-lived 503 with a Retry-After header tells Google to come back later and does not cost rankings. Persistent 503s lasting days or weeks cause Google to reduce crawl frequency and then drop the affected URLs. See 5xx server errors and SEO.
504 Gateway Timeout
What it means: A gateway or proxy did not get a timely response from upstream.
SEO impact: Another temporary 5xx that slows crawling. Repeated 504s signal slow or unresponsive backends; persistent timeouts erode crawl budget and can lead to de-indexing if left unfixed.
Quick reference table
| Code | Meaning | How Google treats it | SEO takeaway |
| 200 | OK | Considered for indexing | Target state for every indexable page |
| 301 | Moved Permanently | Passes signals, replaces old URL | Default for permanent moves |
| 302 | Found (temporary) | Keeps original in index | Short-term moves only |
| 304 | Not Modified | No indexing effect | Caching efficiency, saves crawl budget |
| 307 | Temporary Redirect | Like 302; HSTS 307 not seen by Googlebot | Method-preserving temporary move |
| 308 | Permanent Redirect | Like 301 | Permanent move that preserves method |
| 401 | Unauthorized | Not indexed | Keep public pages off this code |
| 403 | Forbidden | Not indexed; risky for rate limiting | Never use to throttle Googlebot |
| 404 | Not Found | Removed, but lingers for weeks | Correct for genuinely missing pages |
| 410 | Gone | Dropped faster than 404 | Use for deliberate permanent removal |
| 429 | Too Many Requests | Treated like 5xx; slows crawling | A correct way to rate-limit crawlers |
| 500 | Internal Server Error | Slows crawling, retries later | Fix promptly; persistence risks indexing |
| 502 | Bad Gateway | Temporary server error | Check proxies and backends |
| 503 | Service Unavailable | Crawl-safe if brief; drops if sustained | Use with Retry-After for maintenance |
| 504 | Gateway Timeout | Temporary server error | Fix slow backends to protect crawl budget |
When each code actually matters
During a migration: 301 and 308 do the heavy lifting. Map old URLs to their closest new equivalents, avoid chains, and verify the redirects resolve in a single hop.
During maintenance or load spikes: 503 with a Retry-After header is the safe choice, and 429 is the right answer when a specific client is hitting you too hard. Both tell Google to slow down without threatening your index, as long as they are temporary.
When retiring content: 404 is fine for ordinary missing pages, while 410 is the stronger signal when you want removal handled quickly and permanently. If a removed page has a clear replacement, a 301 to that replacement preserves more value than either.
For gated or private content: 401 and 403 keep pages out of the index by design, but they must never touch URLs you actually want ranked.
Common status code mistakes
- Soft 404s. Error pages, empty search results, and out-of-stock pages that return 200 confuse Google. Return a real 404 or 410, or show genuine content.
- Using 302 for permanent moves. This keeps the old URL in the index and delays signal consolidation. Switch to 301 once a move is permanent.
- Rate-limiting with 403 or 404. Google explicitly warns this can remove content from Search. Use 503 or 429 instead.
- Long redirect chains. Each extra hop dilutes signals and burns crawl budget. Redirect straight to the final destination.
- Leaving 5xx errors unfixed. A brief blip is harmless, but days of 5xx or 503 responses lead to dropped URLs. Treat sustained server errors as urgent.
- Returning 200 for redirected pages via JavaScript. Client-side redirects are weaker than server-side codes. Prefer real 3xx responses whenever possible.
A technical audit surfaces soft 404s, redirect chains, accidental 403s, and server errors that quietly drain your crawl budget and rankings.
Frequently asked questions
A 404 for a page that genuinely no longer exists is normal and does not harm the rest of your site. Problems arise only when important pages return 404 by accident, or when you use 404 to rate-limit crawlers.
Both keep the page out of the index. Use 410 when the removal is deliberate and permanent, since Google often drops 410 URLs faster. Use 404 for ordinary missing pages. If a replacement exists, a 301 is usually better than either.
Return 503 Service Unavailable with a Retry-After header. This tells Google the outage is temporary and to come back later, protecting your rankings. Avoid leaving it in place for more than a couple of days.
Not when used correctly for genuinely temporary moves. The problem is using 302 for a permanent move, which keeps the old URL indexed and delays signal consolidation. For permanent changes, use 301 or 308.
Yes. Even though 429 is a 4xx code, Google treats it like a 5xx and slows crawling rather than removing content. It is one of the few safe ways to throttle crawlers, but sustained 429 responses for more than a couple of days can still drop URLs.
No. A 304 is a caching response that tells the crawler the content is unchanged, saving bandwidth and crawl budget. It does not move, remove, or de-index anything.
Claude Vincent is a technical SEO consultant focused on crawlability, rendering, and AI-search visibility. He writes the field guides and case studies at SEO ProCheck, with a bias toward the durable, unglamorous work that decides whether search engines and AI answer engines can actually read and cite a site.
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