Every website migration carries the same risk: the day the new site goes live, years of search visibility can disappear. It happens quietly — a redirect map nobody finished, a canonical pointing at staging, a language folder that changed shape — and it is usually discovered weeks later in a traffic report. This is the checklist we run on every replatforming, redesign and domain change, from the first inventory to the last week of monitoring.
The idea
Search engines do not rank websites; they rank URLs. A migration changes URLs, structure, templates and often content at once, and each change breaks a link in the chain of signals that made the old pages rank. The job of migration SEO is to carry every signal across — or to change it on purpose, with a plan — so that the new site starts where the old one left off.
Three rules underlie everything below: inventory before you design, map one-to-one, and verify on staging before anyone sees the new site.
Why it matters
A well-run migration produces a few weeks of normal fluctuation and then, because the new site is better built, gains. A careless one loses rankings that took a decade to earn and takes months to recover — if the old signals can be recovered at all. The difference is not the platform. It is whether this list was followed.
In practice: the checklist
Before design starts
Full URL inventory — crawl the live site, export Search Console’s pages, pull every URL with organic traffic or backlinks from analytics and a backlink tool. Merge into one list. This is the master.
Benchmark — rankings for the queries that matter, organic traffic by section, Core Web Vitals, indexed page count. You cannot prove a migration succeeded without a “before”.
Content audit — for each URL: keep, improve, consolidate or retire. Retirement is fine; silent disappearance is not.
Decide the structure — URL pattern, language/market structure, section hierarchy. Change it deliberately or keep it. Do not let it drift.
During build
One-to-one redirect map — every old URL that earned traffic or links mapped to the single most relevant new URL. Not the home page. Not a category page unless the content really moved there.
Content model carries metadata — titles, descriptions, canonicals, structured data, hreflang and image alt text migrated as fields, not lost in a copy-paste.
Internal links updated — links inside content point at new URLs directly, not through redirects.
Templates checked against the technical SEO list — headings, canonicals, sitemaps, robots, rendering, performance. See the technical SEO audit checklist.
Staging blocked — noindex and authentication on staging; a plan to remove both at launch.
Before launch (on staging)
Crawl staging with the master list: every old URL should return 301 to a 200 page; no chains, no loops, no redirects to redirects.
Compare pages — old and new versions of the top 100 pages side by side: content present, headings sensible, metadata correct.
Rendering — content visible in raw HTML, not only after JavaScript.
Sitemaps — new sitemaps contain only new, indexable 200 URLs.
hreflang and market pages — every language version present and cross-referenced.
Analytics and Search Console — tracking installed, new property or domain verified, goals working.
Performance — Core Web Vitals at or better than the benchmark.
Launch plan — who does what, in which order, and how to roll back.
Launch day
Remove staging blocks — noindex and robots disallow lifted; confirm with a fetch.
Redirects live — spot-check the top URLs by hand and crawl the master list again from production.
Submit sitemaps in Search Console; request indexing for the most important pages.
Old sitemaps — leave the old sitemap reachable (with old URLs that now redirect) for a few weeks; it helps crawlers discover the moves.
Domain change? — use Search Console’s change-of-address tool.
The first weeks
Daily: Search Console coverage and crawl errors; 404 report; server logs for crawler activity; rankings for the benchmark queries.
Fix immediately: any 404 with traffic or links; any page indexed with the wrong canonical; any redirect chain.
Weekly: traffic by section against the benchmark; Core Web Vitals; indexed page count converging on the expected number.
At three months: compare against the benchmark and write it down. Migration success is a measurement, not a feeling.
What to do
If a migration is planned, put this list in front of the design and engineering team before the first wireframe. If a migration has already gone wrong, start at “launch day”: crawl the old URL list against production, fix the redirects, resubmit sitemaps — most damage is recoverable if it is caught within weeks.
We plan and run migrations as one team — SEO, content, CMS and front-end — which is why the list above is the same list our engineers work from. See website migration services.
FAQ
Will we lose rankings during a migration?
With a one-to-one redirect map, preserved metadata and staging validation, expect brief fluctuation that settles within weeks. Losses come from skipped steps, not from migration itself.
Should every old URL be redirected?
Every URL with traffic, links or a clear equivalent — yes. Retired content with none of those can return a proper 404 or 410; that is honest and search engines handle it well.
Can we redesign and migrate at the same time?
Yes, and most projects do. The condition is that structure and SEO are planned before design starts, not checked at the end.
How long until rankings settle?
Usually two to three months for a large site, with most movement in the first weeks. Monitoring daily in that window is what makes the difference.
Planning a replatforming or redesign? Talk to us before the first wireframe — that is when migration SEO is cheapest.