SEO Migration Services: What to Expect and How to Choose

SEO migration services protect the organic traffic, rankings and revenue your website has already earned while its URLs, platform, design or domain change underneath it. A good provider records what the old site is worth before anyone touches it, maps every URL that matters to its new home, tests the build on staging, checks the launch live and then monitors until Google has settled. A weak one hands your developers a spreadsheet of redirects the week before go-live. This guide covers what the work includes, the order to do it in, what online shops need on top, and the questions that separate a careful migration partner from a hopeful one.

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TL;DR

• A migration is any project that significantly changes your site’s structure, content hierarchy, platform or domain. Each one puts existing rankings at risk if nobody plans for search.
• Proper SEO migration services cover a pre-launch audit and benchmarks, one-to-one redirect mapping, staging tests, launch-day checks and post-launch monitoring. A redirect file on its own isn’t a service.
• Google says 301 and other permanent redirects don’t lose PageRank, but it also says to expect temporary ranking fluctuation and to keep redirects for at least a year.
• Shops need extra checks: filters, variants, discontinued products, checkout, VAT display, product schema and canonicals.
• Cost follows the number of URLs, the platform and how much changes at once, so ask for a scoped quote with named deliverables.

Table of Contents

• What counts as an SEO migration
• What SEO migration services should include
• A migration plan that reduces risk
• Website structure for SEO before and after a move
• Technical SEO for ecommerce migrations
• How to choose an SEO migration agency
• Our perspective
• Plan your migration with Castle
• FAQ
• Sources

What counts as an SEO migration

A website migration is any project that changes a site’s structure or content hierarchy significantly. Search Engine Land’s migration guide lists the usual triggers: changing your domain name, launching a new design or rebrand, consolidating several websites, significantly amending pages and content structure, and re-platforming.

The move itself isn’t the danger. The URLs are. Every address that earns traffic or links today has to either survive or point cleanly to its replacement. The same guide uses WordPress to Shopify as its example: you’ll be forced to change your URL structure, which is always risky for SEO. It also makes a point we agree with. If moving platform is the right decision for the business, it’s the right decision for SEO too, even with some short-term ranking movement. Staying on a platform that’s holding you back because you’re scared of a migration is its own kind of loss.

The migrations we see businesses plan most often:

• Re-platforming, such as WooCommerce or Magento to Shopify, or a move to a headless build.
• Domain change or rebrand, including moves between subdomains and subfolders.
• Redesign that alters navigation, templates or page copy.
• Consolidation of several sites, brands or country versions into one.
• Protocol and housekeeping moves, such as HTTP to HTTPS or a CMS clean-up that touches hundreds of URLs at once.

If your project appears on that list, it’s an SEO migration whether or not anyone has called it one yet.

What SEO migration services should include

Credible providers describe much the same deliverables, and that makes them a good checklist when comparing proposals. A complete service runs across four phases. If a quote only covers one or two, ask who is doing the rest.

Before the build: audit and benchmarks

The team crawls the existing site and records what it has to protect: indexed pages, organic traffic, keyword rankings and the backlinks pointing at each URL. Shopify’s migration checklist recommends a content inventory of every page with its traffic and rankings, plus a backlink inventory listing each external link, the page it points to and its link authority. Semrush suggests setting baseline analytics two to four weeks before the move, so you judge the result against real numbers rather than memory.

This is also when the planned changes get reviewed. Lumar’s checklist advises checking that priority pages are still linked from the primary navigation, that renamed or removed categories are reflected in the redirect rules, and that new templates don’t quietly strip content, internal links, titles or H1s. That last one catches more sites than you’d think. A designer removes an intro paragraph from category pages because it “looked cluttered”, and 200 pages lose the copy that was ranking them.

During the build: redirect mapping and staging

Redirect mapping is the heart of the job. Each old URL gets a one-to-one permanent redirect to the most relevant new page, never a blanket redirect to the homepage. Google Search Central’s site move guide states that 301 and other permanent redirects don’t cause a loss in PageRank, and tells you to keep them for as long as possible, generally at least a year. Anyone who suggests switching redirects off after a few months to “tidy up” the server is giving you bad advice.

Pages that already perform should keep what makes them perform. HubSpot’s migration checklist says migrated pages should contain the same information as before, with the look changing rather than the substance, and warns that mockups or a local environment won’t give you the full picture. Put the build on a test server first.

On staging, the SEO team should check that:

• The redirect file resolves each old URL in one hop, with no chains or loops.
• Canonical tags point to the new URLs, not the old ones or the staging domain.
• The staging site is blocked from indexing, and the block is on the launch checklist to remove.
• Titles, meta descriptions, headings and body copy match the approved map.
• Analytics, consent and conversion tags fire, so you can measure the move from day one.

Launch: timing and live checks

Search Engine Land’s advice is to push the site live between Monday and Thursday and avoid Fridays and peak sales periods, in case something goes wrong. Google’s own guidance is to time the move for a period of lower traffic where possible. Together that rules out a Friday-afternoon launch in the week before Black Friday, which is a sentence we wish we didn’t have to write.

Straight after launch, the team tests a sample of redirects on the live site, submits fresh XML sitemaps and, for a domain or subdomain change, uses the Change of Address tool in Search Console. Google notes that tool is only needed when you move domain or subdomain, not for an HTTP to HTTPS switch or a change of path. It also warns that Google will temporarily crawl the new site more heavily than usual, so the new hosting needs the capacity to cope.

After launch: monitoring

Expect some wobble. Google says to expect temporary fluctuation in rankings during a move, and that for medium-sized sites it can take a few weeks or more for new URLs to replace the old ones in results. Larger sites can take longer. Semrush recommends formal performance reviews at 30, 60 and 90 days after launch, which is a sensible minimum for any monitoring period written into a contract.

A proper service watches index coverage, crawl errors, 404s, redirect chains, traffic and rankings against the benchmarks, and fixes what appears. Google also suggests keeping the old-URL sitemap in Search Console for a while: its indexed count should fall towards zero as the new sitemap’s rises, which gives you a simple progress gauge. Our guide to tracking SEO covers what to watch, and using Google Analytics to improve SEO helps you set up the reporting.

A migration plan that reduces risk

Google’s advice is to split the move into smaller steps where that makes sense, and to change only one thing at a time: move the domain first, for example, then change the layout. In practice that means not launching a new domain, a new design and rewritten copy on the same weekend if you can stage them. When three things change at once and traffic drops, nobody can tell you which one caused it.

Search Engine Land’s nine-step order is a useful frame for the whole project:

1. Meet to set site, business and marketing goals.
2. Run an SEO audit and build a plan.
3. Involve design, with messaging and SEO implications on the table.
4. Develop the site.
5. Make a staging site available for testing.
6. Launch, Monday to Thursday.
7. Test the live site.
8. Run a post-migration SEO audit.
9. Monitor on an ongoing basis.

Notice where SEO appears: step two, before design. Most migration trouble we’re asked to fix started because SEO arrived at step six.

Here’s an illustrative example of why the redirect map deserves the time. Say a shop has 3,000 URLs, and 400 of them bring in organic visits each month, together worth around £18,000 in sales. If a rushed migration leaves 10% of those 400 pages without a sensible redirect, and those 40 pages are the ones carrying a quarter of that revenue, you’re looking at roughly £4,500 a month at risk until someone notices. Prioritising the map by traffic, revenue and links, rather than working through URLs alphabetically, is what stops that happening. Our website launch checklist covers the wider launch tasks that sit alongside the SEO ones.

Website structure for SEO before and after a move

A migration is the best chance you’ll get to fix site architecture, because the URLs are changing anyway. Google’s URL structure guidance recommends a simple URL structure, readable words rather than long ID numbers, hyphens rather than underscores, and trimming unnecessary parameters. It also points out that URLs are case sensitive, so /Boots and /boots are two different addresses to Google.

A practical way to apply this during a move:

• Map the current structure and the planned one side by side before design is signed off.
• Keep commercial pages close to the top, with main categories and services linked from primary navigation.
• Pick URL patterns you won’t need to change again in a year. Dates, campaign names and internal codes in URLs age badly.
• Fold thin or duplicate pages into stronger ones with a redirect, rather than carrying dead weight across.
• Update internal links so content points straight at the new URLs instead of travelling through redirects.

Changing structure and URLs at the same time raises risk, so decide deliberately how much to change in one go, and document every decision in the redirect map.

Technical SEO for ecommerce migrations

Shops carry more URLs, more templates and more ways to break revenue. Catalogue data, faceted navigation and checkout all need testing alongside the SEO checks. Our guide to auditing SEO on an ecommerce website is a good primer, and our overview of technical SEO services explains the underlying work.

Pre-launch checks for shops

ShopWired’s replatforming guide says to test like a customer and like an admin, covering:

• Navigation, search, filters and sorting.
• Product pages, including options, stock messages and delivery information.
• Basket, shipping calculator and checkout, for both guests and account holders.
• Transactional emails, from order confirmation to refunds and password resets.
• VAT display across catalogue, basket, checkout and documents.
• Mobile performance and accessibility basics.
• Redirects for the top 500 legacy URLs.
• Analytics tags, consent banner logic and server-side events.

Test with messy products, not tidy ones. One developer’s ecommerce migration write-up warns against validating only with clean fixtures and suggests test products with many variants, missing images, discounts, out-of-stock states and discontinued status, because real catalogue data is rarely as neat as the design examples. It also draws a line worth keeping: out of stock and discontinued are different. A product that’s coming back keeps its page; a discontinued one needs a policy, whether that’s keeping the page with alternatives, redirecting it, or returning a 404 or 410.

Canonicals, schema and duplicates

Duplicate content is common on shops with variants and filters, and canonical tags tell search engines which version is authoritative. On Shopify, according to its migration checklist, canonicals are set by default and can still be edited for more advanced setups. Product schema should match what shoppers can see: price, availability, brand, SKU or GTIN where available, variants, breadcrumbs and canonical URL, as the same developer guide sets out. It adds a warning we’d underline: don’t mark up hidden product data or stale prices.

Launch-day routine for shops

ShopWired’s launch plan is a good model to adapt:

1. Pick a quiet trading window and lower the DNS TTL 24 to 48 hours beforehand.
2. Put a maintenance page on the old site and lock admin changes.
3. Run delta imports for products, stock and orders.
4. Deploy the redirect file and verify a sample.
5. Remove the indexing blocks on the new site.
6. Switch DNS and confirm SSL works end to end.
7. Submit fresh XML sitemaps in Google Search Console and Bing Webmaster Tools.
8. Place a real order, refund it, and check the notifications.

The same guide recommends keeping a small team on call for the first 48 hours. We’d add one more name to that rota: whoever owns the redirect map.

How to choose an SEO migration agency

Every provider ranking for this search promises to protect your rankings, so judge them on process and evidence instead. These are the questions we’d ask, and what a strong answer sounds like.

Do you benchmark before launch?

• A strong answer: crawl, traffic, rankings and backlink data recorded weeks in advance, shared with you as the baseline.

How is redirect mapping done?

• A strong answer: one-to-one, prioritised by traffic, revenue and links, with pattern rules only for low-value URLs.

Are you involved during the build?

• A strong answer: SEO input at design and on staging, not a sign-off the day before launch.

What happens after launch?

• A strong answer: a defined monitoring period, with reviews at around 30, 60 and 90 days and fixes included.

Who does the work?

• A strong answer: a named team, ideally with SEO and development under one roof, rather than hand-offs between suppliers.

How do you report?

• A strong answer: reporting tied to enquiries and revenue against the baseline, not only rankings.

Price is usually the next question. We don’t publish a flat fee for migrations, because the cost follows the number of URLs, the platform, whether the domain changes and how much development support is needed. Ask any provider for a scoped quote that lists deliverables and the monitoring period, then compare like for like. Be wary of anyone who guarantees no traffic loss; Google itself says to expect fluctuation. Our guide to how long SEO takes to work helps set expectations for recovery and growth afterwards.

Our perspective

Most migration damage isn’t caused by the move. It’s caused by decisions made without anyone looking at search data: a category renamed because it sounded better in a workshop, a redirect file treated as an afterthought, a launch on a Friday because that’s when the developer finished.

We treat a migration as a joint project between SEO, design and development, and that’s much easier when one in-house team does all three. We also look beyond the classic results page now. Visibility includes answers in tools such as ChatGPT and Gemini, and the things a migration should get right anyway (clean structure, consistent URLs, content that renders in the HTML, accurate schema) help with both.

Our aim is reporting tied to enquiries and revenue, so you can see whether the move has held and where it’s growing. And if a migration is also a chance to rethink structure, we’d rather do that properly before launch than patch it for six months afterwards.

Plan your migration with Castle

If you’re re-platforming, redesigning or changing domain, we can audit the current site, build the redirect map and help you launch with your search visibility intact. SEO, web design and Shopify development are handled by one in-house team, so nothing gets lost between suppliers. You can see the full range on our services page.

Tell us what you’re planning and when, and we’ll tell you where the risk sits.

Talk to our SEO team

FAQ

How long does it take to recover after a site migration?

Google says that for medium-sized sites it can take a few weeks or more for new URLs to replace old ones in results, and that larger sites can take longer. Temporary ranking fluctuation is expected while pages are recrawled, which is why monitoring should continue for at least 90 days after launch.

Do 301 redirects lose rankings?

Google Search Central states that 301 and other permanent redirects don’t cause a loss in PageRank. Problems come from missing redirects, redirects to irrelevant pages and long redirect chains. Mapping each old URL to its closest equivalent, and keeping redirects for at least a year, avoids most of them.

What is the best day to launch a migrated website?

Search Engine Land recommends going live between Monday and Thursday and avoiding Fridays and peak sales periods, and Google suggests timing the move for lower traffic. That leaves working days to catch and fix issues. For shops, pick the quietest trading window you have.

Should I change my site structure during a migration?

Often yes, because the URLs are changing anyway, but change deliberately. Google advises changing one thing at a time where possible. Keep commercial pages near the top of the navigation, use simple readable URLs, and make sure every restructured URL has a mapped redirect.

Do I need Google’s Change of Address tool?

Only if you’re moving from one domain or subdomain to another. Google says it isn’t needed for an HTTP to HTTPS move, a www change on the same domain or a change of URL paths.

Sources

• Site moves with URL changes, Google Search Central
• URL structure best practices for Google Search, Google Search Central
• Website migrations: a plan to keep your traffic and SEO safe, Search Engine Land
• Website migration checklist, HubSpot
• Complete Website Migration Checklist, Semrush
• Website Migration Checklist for SEO, Lumar
• Ecommerce Replatforming guide, ShopWired
• SEO Site Migration Checklist, Shopify UK
• E-Commerce SEO Migration in Next.js, John Kavanagh

Recommended

• Technical SEO Services: What They Include and How to Choose
• What Ecommerce SEO Costs in the UK, What It Includes and How to Choose
• How to Choose a Shopify Agency: What It Costs and What to Check