SurfSense/.cursor/skills/technical-seo-checker/references/http-status-codes.md

HTTP Status Codes for SEO

SEO-relevant HTTP status codes, their implications, and how to diagnose and fix issues.

Status Code Categories

• 2xx: Success - Request succeeded
• 3xx: Redirection - Further action needed
• 4xx: Client Error - Problem with the request
• 5xx: Server Error - Server failed to fulfill request

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2xx Success Codes

200 OK

What it means: Request succeeded, content returned normally.

SEO impact: Positive - page is accessible and indexable.

When to use: Standard response for all working pages.

When it's a problem: When different URLs return 200 for same content (should use 301 redirect).

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204 No Content

What it means: Request succeeded but no content to return.

SEO impact: Neutral - rarely used for pages meant to be indexed.

Common use: API responses, AJAX requests.

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3xx Redirection Codes

301 Moved Permanently

What it means: Resource permanently moved to new URL. All link equity transfers.

SEO impact: Positive when used correctly - passes 90-99% of link equity.

When to use:

• Permanently changing URL structure
• Consolidating duplicate content
• Moving to new domain
• Changing HTTP to HTTPS
• Changing www to non-www (or vice versa)

Example header:

HTTP/1.1 301 Moved Permanently
Location: https://example.com/new-page

Common mistakes:

• Using 302 instead of 301 for permanent changes
• Creating redirect chains (A→B→C)
• Redirecting to irrelevant pages
• Not redirecting HTTP to HTTPS

How to implement:

• .htaccess (Apache): Redirect 301 /old-page /new-page
• nginx: rewrite ^/old-page$ /new-page permanent;
• Server-side: Set Location header with 301 status

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302 Found (Temporary Redirect)

What it means: Resource temporarily at different URL. Original URL should still be used.

SEO impact: Neutral to negative - does NOT pass full link equity. Search engines keep indexing original URL.

When to use:

• A/B testing
• Temporary promotions
• Maintenance redirects
• Geolocation redirects (sometimes)

When NOT to use: Permanent URL changes (use 301).

Warning: Google may treat long-standing 302s as 301s, but better to be explicit.

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303 See Other

What it means: Response can be found at another URI using GET.

SEO impact: Minimal - rarely used for SEO purposes.

Common use: After form submissions, redirect to results page.

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307 Temporary Redirect

What it means: Temporary redirect that preserves request method (POST stays POST).

SEO impact: Similar to 302 - temporary, doesn't pass full link equity.

Difference from 302: Guarantees request method won't change (more precise than 302).

When to use: Temporary redirects where HTTP method preservation matters.

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308 Permanent Redirect

What it means: Permanent redirect that preserves request method.

SEO impact: Similar to 301 - passes link equity.

Difference from 301: Guarantees request method won't change (POST stays POST).

When to use: Permanent redirects where method preservation matters (rare for SEO).

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Redirect Chain Issues

Problem: Multiple redirects before reaching final destination.

Example chain:

http://example.com/page
  → https://example.com/page (redirect 1)
  → https://www.example.com/page (redirect 2)
  → https://www.example.com/new-page (redirect 3)

SEO impact:

• Slows page load (each redirect = new HTTP request)
• Dilutes link equity with each hop
• Wastes crawl budget
• Poor user experience

How to fix: Redirect directly from original URL to final destination.

Fixed version:

http://example.com/page
  → https://www.example.com/new-page (single redirect)

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Redirect Loops

Problem: Redirects create infinite loop.

Example:

/page-a → /page-b
/page-b → /page-a

SEO impact: Severe - page completely inaccessible.

Symptoms:

• Browser shows "Too many redirects" error
• Page never loads
• Search Console shows crawl errors

How to diagnose:

1. Use redirect checker tool
2. Check .htaccess or nginx config for conflicting rules
3. Review server-side redirect logic

How to fix:

1. Identify conflicting redirect rules
2. Remove or correct the loop
3. Test thoroughly
4. Request recrawl in Search Console

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4xx Client Error Codes

404 Not Found

What it means: Requested resource doesn't exist.

SEO impact: Neutral to negative depending on context.

When 404s are OK:

• Legitimately deleted pages with no equivalent
• Never-existed URLs from typos
• Temporary content that expired (old promotions)
• Intentionally removed low-quality content

When 404s are problems:

• Pages that should exist are returning 404
• Previously working pages now broken
• Important pages missing from navigation
• High-traffic pages deleted without redirect

How to fix:

1. If content moved: Set up 301 redirect to new location
2. If content deleted: Either keep 404 or redirect to relevant category
3. If never existed: Leave as 404
4. If important: Restore the page

Monitoring 404s:

• Check Search Console → Coverage → Not found (404)
• Review referrer data to see what's linking to 404s
• Fix high-value 404s first (most traffic/backlinks)

Soft 404s (BAD):

• Page returns 200 but shows "not found" message
• Search engines may keep page indexed
• Creates duplicate content issues
• Fix: Return proper 404 status code

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410 Gone

What it means: Resource permanently deleted, never coming back.

SEO impact: Stronger signal than 404 - tells search engines not to return.

When to use:

• Discontinued products
• Expired promotions
• Permanently removed content
• Outdated information

Difference from 404:

• 404: "Not found" (might exist at another URL)
• 410: "Gone forever" (don't look for it)

When to use 410 vs 301:

• Use 410: No equivalent replacement exists
• Use 301: Relevant alternative exists

How search engines respond:

• Faster de-indexing than 404
• Stop crawling sooner
• Better for crawl budget

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403 Forbidden

What it means: Server understood request but refuses to authorize it.

SEO impact: Negative - page inaccessible and won't be indexed.

Common causes:

• Permission restrictions
• IP blocking
• .htaccess restrictions
• File permissions (chmod)
• Authentication required

When it's intentional:

• Admin areas
• Member-only content
• Geographic restrictions

When it's a problem:

• Public pages returning 403
• Search engine bots blocked
• Accidental permission changes

How to diagnose:

1. Check .htaccess for IP restrictions
2. Verify file permissions (should be 644 for files, 755 for directories)
3. Check server-level access rules
4. Test with different IPs/user-agents

How to fix:

1. Adjust file permissions: chmod 644 filename
2. Remove blocking rules from .htaccess
3. Whitelist search engine bots
4. Review server firewall rules

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401 Unauthorized

What it means: Authentication required but not provided or failed.

SEO impact: Negative - page won't be indexed.

Common causes:

• Password-protected pages
• HTTP Basic Authentication
• Expired sessions
• Missing credentials

When it's intentional: Member areas, staging sites, admin panels.

How to handle for SEO:

• Don't password-protect pages you want indexed
• Use separate staging domain with 401
• For members-only content, show teaser with meta robots noindex

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429 Too Many Requests

What it means: User/bot sent too many requests in given timeframe (rate limiting).

SEO impact: Negative if search engines can't crawl.

Common causes:

• Aggressive crawling
• DDoS protection triggered
• API rate limits
• Server throttling

How to handle:

1. Check Googlebot isn't being rate-limited (use Search Console)
2. Whitelist verified search engine bots
3. Configure rate limits appropriately
4. Monitor crawl rate in Search Console

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5xx Server Error Codes

500 Internal Server Error

What it means: Generic server error, something went wrong.

SEO impact: Very negative if persistent - prevents indexing and ranking.

Common causes:

• PHP/code errors
• Database connection issues
• .htaccess syntax errors
• Resource limits exceeded
• Plugin/theme conflicts (WordPress)

How to diagnose:

1. Check server error logs
2. Review recent code/config changes
3. Test locally or on staging
4. Disable plugins one by one (if CMS)
5. Check .htaccess syntax

How to fix:

1. Review error logs for specific error
2. Roll back recent changes
3. Fix code errors
4. Increase resource limits if needed
5. Test thoroughly before re-deploying

Monitoring: Set up alerts for 500 errors (sudden spike = problem).

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502 Bad Gateway

What it means: Server received invalid response from upstream server.

SEO impact: Negative if persistent - prevents crawling/indexing.

Common causes:

• Proxy/load balancer issues
• Upstream server down
• Timeout issues
• Firewall blocking

Common scenarios:

• CDN can't reach origin server
• Application server crashed
• Database server unresponsive

How to fix:

1. Check upstream server status
2. Verify firewall rules
3. Check timeout settings
4. Restart proxy/load balancer if needed
5. Review CDN configuration

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503 Service Unavailable

What it means: Server temporarily unable to handle request.

SEO impact: Neutral if truly temporary with Retry-After header. Negative if prolonged.

Common causes:

• Maintenance mode
• Server overload
• Database down
• Resource exhaustion

Proper use for maintenance:

HTTP/1.1 503 Service Unavailable
Retry-After: 3600

Best practices for maintenance:

1. Use 503 (not 404 or 500)
2. Include Retry-After header
3. Keep maintenance brief (<24 hours)
4. Schedule during low-traffic times
5. Inform users with clear message

How search engines handle 503:

• Short-term (hours): Will retry, no ranking impact
• Long-term (days+): May drop rankings, de-index pages

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504 Gateway Timeout

What it means: Server didn't receive timely response from upstream server.

SEO impact: Negative - prevents crawling.

Common causes:

• Slow database queries
• External API timeouts
• Insufficient server resources
• Network issues

How to fix:

1. Optimize slow queries
2. Increase timeout limits
3. Add caching
4. Scale server resources
5. Review external dependencies

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Status Code Decision Flowchart

Content Moved Permanently?

→ YES: Use 301 redirect → NO: Continue

Content Moved Temporarily?

→ YES: Use 302 redirect → NO: Continue

Content Deleted with No Replacement?

→ YES: Use 404 (or 410 if permanently gone) → NO: Continue

Content Exists at This URL?

→ YES: Use 200 OK → NO: Use 404

Need Authentication?

→ YES: Use 401 → NO: Continue

Access Forbidden?

→ YES: Use 403 → NO: Continue

Server Error?

→ YES: Use 500, 502, 503, or 504 depending on cause → NO: Use 200 OK

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Diagnosing Status Code Issues

Tools

Browser DevTools:

1. Open DevTools (F12)
2. Go to Network tab
3. Reload page
4. Check status code in first request

cURL command:

curl -I https://example.com/page

Online checkers:

• httpstatus.io
• redirect-checker.org
• websiteplanet.com/webtools/redirects/

Google Search Console:

• Coverage report → Error/Excluded sections
• URL Inspection tool → Check specific URLs

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Common Diagnostic Scenarios

"Page Won't Index"

Check:

1. Status code (should be 200)
2. Redirects (shouldn't redirect away)
3. 4xx/5xx errors
4. robots.txt blocking
5. noindex meta tag

"Page Disappeared from Results"

Check:

1. Returns 404/410/5xx
2. Redirecting elsewhere (301/302)
3. Changed to 403/401
4. Server timing out (504)

"Traffic Dropped After Migration"

Check:

1. Old URLs return 404 (should be 301)
2. Redirect chains (should be direct)
3. Redirect loops
4. Wrong redirect type (302 vs 301)
5. Incorrect redirect targets

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Status Codes and Crawl Budget

Impact on Crawl Budget

Efficient (minimal impact):

• 200 OK
• 301 redirects (if minimal chains)
• 410 Gone (removes from crawl queue)

Moderate impact:

• 302 redirects (search engine may keep checking)
• 404 errors (search engines periodically recheck)
• Redirect chains (multiple requests per URL)

High impact (wasteful):

• 5xx errors (search engines retry frequently)
• Redirect loops (waste crawl budget)
• Soft 404s (search engine confused, keeps crawling)
• 429 rate limiting (prevents efficient crawling)

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SEO Status Code Best Practices

For Migrations

• Use 301 redirects for all permanently moved pages
• Redirect directly to final destination (no chains)
• Test all redirects before launching
• Keep redirects in place for at least 1 year
• Monitor 404 errors in Search Console post-launch
• Map 1:1 where possible (old URL → equivalent new URL)

For Deleted Content

• Use 301 if relevant replacement exists
• Use 404 if no replacement and might return
• Use 410 if permanently gone, never returning
• Don't redirect to irrelevant pages (creates soft 404)
• Create custom 404 page with search and navigation

For Maintenance

• Use 503 with Retry-After header
• Keep maintenance window brief (<24 hours)
• Create user-friendly maintenance page
• Inform users of expected downtime
• Monitor Search Console for crawl issues

For Performance

• Minimize redirect chains
• Fix redirect loops immediately
• Monitor 5xx errors closely
• Set up alerts for sudden status code changes
• Optimize to reduce 504 timeouts

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Status Code Monitoring

Key Metrics to Track

In Search Console:

• Crawl errors by type
• Server errors (5xx) trend
• Not found (404) trend
• Redirect errors

In analytics:

• 404 page views
• Entry pages with high exit rate (might be errors)
• Sudden traffic drops (could indicate status code issues)

Server logs:

• Status code distribution
• 5xx error frequency
• Unusual patterns

Setting Up Alerts

Alert on:

• Sudden increase in 5xx errors
• Increase in 404 errors
• New redirect chains
• Crawl error spikes in Search Console

Tools:

• Google Search Console email alerts
• Server monitoring (UptimeRobot, Pingdom)
• Log analysis tools
• Custom scripts for log monitoring

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Quick Reference Table

Code	Name	SEO Impact	Use When	Passes Link Equity?
200	OK	✅ Positive	Page works normally	N/A (original URL)
301	Moved Permanently	✅ Positive	Permanent URL change	✅ Yes (~90-99%)
302	Found	⚠️ Neutral	Temporary redirect	❌ No
307	Temporary Redirect	⚠️ Neutral	Temporary (method preserved)	❌ No
308	Permanent Redirect	✅ Positive	Permanent (method preserved)	✅ Yes
404	Not Found	⚠️ Neutral	Content doesn't exist	N/A
410	Gone	⚠️ Neutral	Permanent deletion	N/A
403	Forbidden	❌ Negative	Access denied	N/A
401	Unauthorized	❌ Negative	Auth required	N/A
500	Internal Server Error	❌ Negative	Server error	N/A
502	Bad Gateway	❌ Negative	Upstream error	N/A
503	Service Unavailable	⚠️ Neutral	Temporary downtime	N/A
504	Gateway Timeout	❌ Negative	Timeout error	N/A

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Status Code Testing Checklist

Before launching site changes:

• Test all redirects return correct status codes
• Verify no redirect chains exist
• Check no redirect loops present
• Confirm important pages return 200
• Ensure deleted pages return 404/410 (not 200)
• Verify 301s point to correct destinations
• Test with multiple user-agents
• Check status codes in Search Console
• Monitor server logs for unusual patterns
• Set up alerts for error spikes

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Technical SEO Severity Framework

Issue Classification

Severity	Impact Description	Examples	Response Time
Critical	Prevents indexation or causes site-wide issues	Robots.txt blocking site, noindex on key pages, site-wide 500 errors	Same day
High	Significantly impacts rankings or user experience	Slow page speed, missing hreflang, duplicate content, redirect chains	Within 1 week
Medium	Affects specific pages or has moderate impact	Missing schema, suboptimal canonicals, thin content pages	Within 1 month
Low	Minor optimization opportunities	Image compression, minor CLS issues, non-essential schema missing	Next quarter

Technical Debt Prioritization Matrix

Factor	Weight	Assessment
Pages affected	30%	Site-wide > Section > Single page
Revenue impact	25%	Revenue pages > Blog > Utility pages
Fix difficulty	20%	Config change < Template change < Code rewrite
Competitive impact	15%	Competitors passing you > parity > you ahead
Crawl budget waste	10%	High waste > Moderate > Minimal

Core Web Vitals Optimization Quick Reference

LCP (Largest Contentful Paint) Optimization

Root Cause	Detection	Fix
Large hero image	PageSpeed Insights	Serve WebP, resize to container, add loading="lazy"
Render-blocking CSS/JS	DevTools Coverage	Defer non-critical, inline critical CSS
Slow server response	TTFB >800ms	CDN, server-side caching, upgrade hosting
Third-party scripts	DevTools Network	Defer/async, use facade pattern

CLS (Cumulative Layout Shift) Optimization

Root Cause	Detection	Fix
Images without dimensions	DevTools	Add explicit width/height attributes
Ads/embeds without reserved space	Visual inspection	Set min-height on containers
Web fonts causing FOUT	DevTools	font-display: swap + preload fonts
Dynamic content injection	Visual inspection	Reserve space with CSS

INP (Interaction to Next Paint) Optimization

Root Cause	Detection	Fix
Long JavaScript tasks	DevTools Performance	Break into smaller tasks, use requestIdleCallback
Heavy event handlers	DevTools	Debounce/throttle, use passive listeners
Main thread blocking	DevTools	Web workers for heavy computation