What is a 301 Redirect?

301 Redirect: permanent moves search engines should remember

A 301 redirect is an HTTP response with status code 301 and a Location header pointing to the new URL. It communicates Moved Permanently: the resource at the requested address now lives elsewhere, and future requests should use the new location.

For SEO, 301 is the workhorse for domain migrations, URL restructuring, trailing-slash normalization, and retiring duplicate paths. It consolidates indexing signals toward one canonical destination faster and more reliably than meta refresh or JavaScript redirects.

301 response anatomy

GET /old-blog/post HTTP/1.1
Host: example.com

HTTP/1.1 301 Moved Permanently
Location: https://example.com/blog/post
Content-Length: 0

Browsers navigate users to the destination. Crawlers record the redirect, fetch the target, and over time associate rankings and link equity with the new URL.

301 vs other redirect codes

For standard HTML page moves, 301 and 308 both signal permanence. Most CMS and Apache/Nginx configs default to 301 for "permanent redirect" rules.

When to use 301 redirects

Domain and protocol changes

# Apache example
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]

HTTP → HTTPS, www → apex (or vice versa), and country TLD consolidation all warrant 301.

Content merges and retirements

Two overlapping articles become one stronger piece. The weaker URL 301s to the survivor. External backlinks and historical indexed URLs transfer intent without duplicate content competition.

Parameter and slug cleanup

/product?id=8821 permanently becomes /products/wireless-headphones. One hop, stable slug, cleaner crawl path.

When 301 is wrong

Redirecting every 404 to the homepage is a common 301 misuse. Google may still crawl the destination but treat the source intent as unmatched.

SEO implications of 301 redirects

Signal consolidation

Link equity from external sites pointing at the old URL flows toward the destination after Google processes the redirect. Internal links should be updated to the final URL to avoid unnecessary hops—redirect chains waste crawl budget.

Index swap timeline

Expect weeks, not hours. Google must recrawl the old URL, follow the 301, reprocess the destination, and update SERPs. Sudden traffic drops after migration often mean incomplete redirect maps or blocked destination URLs.

Sitemap and canonical alignment

After 301 deployment:

• Remove old URLs from XML sitemaps
• List only final URLs
• Ensure canonical tags on the destination self-reference the new address
• Update hreflang and internal navigation

Crawl behavior

Googlebot continues requesting old URLs found in external links. Permanent 301s are correct—they teach the ecosystem the new address while old references decay.

Implementation examples

Nginx

server {
    location /legacy-guide {
        return 301 https://example.com/guides/new-guide;
    }
}

Express (Node.js)

app.get('/old-path', (req, res) => {
  res.redirect(301, 'https://example.com/new-path');
});

PHP

header('HTTP/1.1 301 Moved Permanently');
header('Location: https://example.com/new-path');
exit;

Cloudflare Page Rule (conceptual)

Forward http://* to https://* with 301 at the edge before origin load.

Always use absolute Location URLs in cross-host redirects to avoid ambiguous resolution.

301 redirect chains and loops

Ideal path:

/old-url → (301) → /final-url → (200 OK)

Problem path:

/old-a → 301 → /old-b → 301 → /old-c → 301 → /final

Google tolerates limited chaining; SEO best practice is one hop. Redirect loops (A → B → A) block retrieval entirely—critical crawl errors.

Example: retailer category restructure

shop.example/women/dresses moved to shop.example/clothing/dresses during navigation redesign. Engineers deployed 301 but forgot /women/dresses?color=red parameter variants.

Outcome:

• Clean path consolidated within three weeks
• Parameter URLs returned 404 for six months—backlinks to filtered views lost equity
• Fix: regex 301 rule covering query strings; parameter handling documented

Post-fix crawl showed single-hop 301s and rising indexed count on the new hierarchy.

Testing 301 redirects

curl -I -A "Googlebot" https://example.com/old-url

Confirm status 301, single Location header, and destination 200 OK. Use crawl tools to map redirect graphs after migrations.

How Crawlox helps with 301 redirects

Crawlox maps redirect chains across your authorized crawl: which URLs 301, hop count, final destinations, and broken endpoints. After migrations, compare before-and-after graphs to find orphan 302s, accidental chains, and old URLs still linked internally without passing through a single-hop 301 to the correct final URL.