<objective> Covers redirect and migration planning: the 301/302/307/308 status-code decision table and their SEO/link-equity impact, the full migration checklist (URL mapping CSV, implementing 301s, staging tests, updating internal links and sitemap, Search Console Change of Address, 90-day 404 monitoring), redirect-chain and redirect-loop detection and fixes, common redirect patterns (HTTP→HTTPS, www/non-www, trailing slash, slug changes), and anti-patterns (mass redirect-to-homepage, soft 404s, JS-based redirects, meta-refresh redirects). </objective>

Redirects & Migrations

Status Codes

Code	Use Case	SEO Impact
301	Permanent move	Passes ~99% link equity
302	Temporary (e.g. A/B test)	Does NOT pass equity long-term
307	Temporary, preserves HTTP method	Same as 302 for SEO
308	Permanent, preserves HTTP method	Same as 301 for SEO

Migration Plan

1. Map old URLs → new URLs (CSV: source, target, status)
2. Implement 301s for every old URL
3. Test in staging with curl -I <old-url> → expect 301 Location: <new>
4. Update internal links to point directly to new URLs (avoid chain)
5. Update sitemap.xml with new URLs only
6. Submit to Google Search Console via Change of Address tool (if domain change)
7. Monitor 404s for 90 days post-launch

Chain Detection

• Chain: A → B → C (loses ~10% equity per hop)
• Loop: A → B → A (infinite, broken)
• Fix: A → C directly

Common Redirects

From	To	Status
http://	https://	301
www.	non-www (or reverse, pick one)	301
/page/	/page (or reverse)	301
Old slug	New slug	301

Anti-Patterns

• ❌ Redirecting everything to homepage (mass 404 → 301 to /) → looks spammy
• ❌ Soft 404s (200 status on missing pages)
• ❌ JS-based redirects (Google may not follow)
• ❌ Meta refresh redirects > 0s (use server-side)