SEO Site Migration: The Complete Checklist (Move Without Losing Rankings)

An SEO site migration is any change that alters your site's URLs, structure, platform, domain, or design in a way that affects how search engines crawl, index and rank it. Done carelessly, a migration can erase years of SEO equity overnight; done methodically, it preserves rankings and often improves them. The difference is almost entirely down to one thing: a complete, tested redirect map.

This guide is a supporting page to Unity SEO's Technical SEO pillar. Norfolk competitors sell migrations as a service but publish no guidance on how to do them safely — this is the playbook.

When You're Doing a Migration (Often Without Realising)

Any of these is a migration that needs the full process:

• Domain change (rebrand, new business name)
• HTTP → HTTPS or www ↔ non-www change
• Platform/CMS change (e.g. WordPress → Astro)
• URL structure change (new slugs, removed folders, new taxonomy)
• Site redesign that changes content, structure or URLs
• Site consolidation (merging multiple sites) or internationalisation

If URLs change, it's a migration. Treat it as one.

Phase 1 — Before: Inventory & Plan

The whole project succeeds or fails here.

1. Crawl the existing site in full with Screaming Frog or Sitebulb. Export every indexable URL, including ones not in your sitemap that are still crawled (Brand Vision).
2. Build a master URL inventory in a spreadsheet, enriched with:

• Organic traffic per URL (GA4 + Search Console)
• Backlink equity per URL (Ahrefs/Semrush/Moz) — identify pages with valuable external links
• Current rankings for tracked terms (benchmark to measure impact afterwards)

1. Classify every URL into four buckets (Brand Vision):

• Keep — same URL, content preserved
• Move — content kept, URL changes → needs a 301
• Merge — combined into another page → 301 to the consolidated URL
• Remove — genuinely retired → 301 to the most relevant alternative, or 410 if no equivalent

1. Benchmark everything now: rankings, organic traffic, indexed page count, Core Web Vitals, conversions. You cannot measure migration impact without a pre-migration baseline.

Phase 2 — Build: The Redirect Map

The redirect map is the single most important deliverable.

• Map every old URL to its single best new URL, one row per URL, combining your inventory data.
• Use 301 (permanent) redirects — they pass ranking signals. Avoid 302s for permanent moves.
• Never chain redirects. A → B → C should be rewritten as A → C and B → C. Redirect chains waste crawl budget and leak equity.
• Never redirect everything to the homepage. Redirect to the closest equivalent page; bulk homepage redirects are treated as soft 404s and lose the equity entirely.
• Self-canonicalise and update internal links on the new site so they point directly to final URLs, not through redirects.
• Create a custom, helpful 404 page for the genuinely-gone URLs.

Phase 3 — Staging: Test Before You Launch

• Build on a staging environment blocked from indexing (robots.txt disallow + noindex + ideally HTTP auth). Remember to remove these blocks at launch — leaving them on is a catastrophic, common error.
• Test the redirect map on staging: every old URL resolves with a single 301 to the correct, live new URL.
• QA the technical foundations: titles, meta, headings, canonical tags, structured data, XML sitemap, internal links, Core Web Vitals.
• Verify analytics and Search Console tracking are in place on the new site.

Phase 4 — Launch: Go Live

1. Activate redirects and update DNS.
2. Confirm staging blocks are removed (robots.txt opened, noindex stripped from production).
3. Submit the new XML sitemap in Google Search Console; for a domain change, use the Change of Address tool.
4. Keep the old domain/redirects live indefinitely — never decommission them.
5. Test a sample of high-value redirects live immediately.

Phase 5 — After: Monitor & Recover

• Watch Search Console daily for the first 2 weeks, then weekly: indexing status, crawl errors, coverage of new URLs, manual actions.
• Expect a temporary dip. Some volatility for 2–4 weeks is normal as Google re-processes the site.
• Audit non-recovered pages by month two. For pages that ranked well before but haven't recovered, check content integrity, redirect correctness, and internal links (First Page).
• Compare against your pre-migration baseline — rankings, traffic, indexed count — to quantify impact and isolate problems.

The Migration Checklist (Condensed)

Before: full crawl • URL inventory with traffic + backlinks + rankings • classify Keep/Move/Merge/Remove • benchmark everything Build: 301 redirect map • no chains • no homepage dumping • update internal links • custom 404 Staging: index-blocked staging • test redirects • QA technical foundations • verify tracking Launch: activate redirects + DNS • remove staging blocks • submit sitemap • Change of Address (if domain) • keep old redirects live After: daily GSC monitoring • audit non-recovered pages • compare to baseline

Planning a migration? Unity SEO runs it for you — inventory, redirect mapping, staging QA and post-launch recovery monitoring. Part of the Technical SEO pillar.

Sources: Brand Vision SEO Migration Checklist; First Page Website SEO Migration Checklist; Link Whisper 29-Point Migration Checklist; Google crawl budget documentation.