Website Migration SEO Checklist: How to Redesign, Replatform or Change Domain Without Losing Search Traffic

A new design, platform or domain can go well for the business and badly for search. The usual cause is old pages that stopped working, pages nobody recorded and settings nobody checked before launch.

Quick answer: record what the old site earns before you change anything, map every old URL to its closest new page with a single redirect, check the staging site for mistakes that hide pages from search, test the live site on launch day and watch it closely for four weeks. No migration is risk free, and nobody can guarantee rankings afterwards. The aim is to remove avoidable losses and spot the rest quickly.

For the detail of a full technical review, see our technical SEO audit checklist.

Before you start: record the baseline

You cannot tell whether a migration worked without a record of the old site. Take it before the first change.

• Every URL. Combine a crawl of the site, the sitemap and your CMS.
• Pages that earn search visits. Export landing pages and queries from Google Search Console and Google Analytics 4.
• Pages that earn links. Note which pages other sites link to.
• Current rankings for the phrases that matter most.
• Enquiries, counted by landing page.

A page with no visits, links or enquiries is a candidate for removal. A page with all three must not be lost.

The redirect map

A redirect tells browsers and search engines that a page has moved. The redirect map lists where each old URL goes. The rules are short:

1. One step. Each old URL goes straight to its final new URL, not through a chain.
2. The closest matching new page. An old service page goes to the new page for that service.
3. Never everything to the home page. If there is no equivalent, use the nearest relevant section or let the URL return a proper 404 page.
4. Cover the variants: with and without www, with and without a trailing slash, and old campaign URLs.

Test the map by crawling the full list and checking each old URL ends on the intended page in one hop.

Staging checks

Test the new site on a staging copy first.

• Titles and descriptions are present, unique and carried over where the old ones worked.
• Canonical tags point to each page’s own final address, not the staging domain or the old site.
• Noindex left on by mistake. Staging sites are often set to stay out of search. If that setting survives into launch, the live site asks search engines to ignore it.
• Robots rules on the live site do not block crawling.
• Internal links point to new addresses directly, not through redirects.
• Structured data is still present, valid and describing the right page.
• Page speed on key templates is no worse than before.

Launch day

• Switch the redirects on when the new site goes live.
• Confirm noindex and any crawl block are off.
• Check the sitemap lists only new, final URLs, then submit it in Google Search Console. For a domain change, use the change-of-address steps Search Console offers.
• Open a sample of old URLs and confirm each redirects once, correctly.
• Submit a test enquiry and check the analytics records it.
• Keep the old site’s files so you can roll back.

An example from our own site

This is our own site, not a client’s. In September 2026 a redirect rule meant to remove trailing slashes sent every missing URL into a redirect loop, because our host ignores the trailing slash when matching rules. Removing the rule did not work at first, because a generated configuration file committed by mistake still held the old rule. The fix was to remove both and add a proper 404 page. On 30 September 2026 a missing URL returned a 404, and a real page with a trailing slash returned one 301 to the clean URL. We are not claiming any effect on rankings or traffic.

The first four weeks after launch

When	Check	Normal	Worry
Days 1 to 3	Status codes, sitemap, enquiries	A few 404s from old links	Live pages returning errors or carrying a block
Week 1	Search Console coverage and errors	Old URLs drop out and new ones appear gradually	Important pages reported as excluded
Weeks 2 to 3	Visits and rankings against the baseline	Movement up and down while pages are reprocessed	A key page that has vanished and is not recovering
Week 4	Enquiries, links, speed	A settled pattern you can compare	Fewer enquiries with no other explanation

Some movement is normal, because search engines need time to reprocess a changed site. A dip that is shrinking is different from a fall that is not. If a page that mattered has vanished, check the redirect map and staging checks first.

When to ask for help

A technical SEO audit starts from £1,500 plus VAT and can be run before launch to review the redirect map and the staging site. Monitoring afterwards sits inside our SEO and AI search retainer at £1,750 a month plus VAT, with a three-month minimum. See pricing, or technical SEO in Manchester.