Website migration SEO: replatforming without losing revenue

8 min read

Website migration SEO: replatforming without losing revenue

8 min read

Key takeaways

Most lasting traffic loss after a replatform comes from avoidable errors such as missing redirects, thinner templates and uncontrolled filter pages, not from the new platform itself.
Google says a site move brings temporary ranking fluctuation, and that medium-sized sites can take a few weeks or more to show the new URLs; larger sites take longer.
Shopify fixes its product and collection paths and only redirects URLs that no longer exist, so most Magento or Adobe Commerce URLs will change and need mapping.
Baseline revenue and clicks by URL before anything changes, map every valuable URL to its closest equivalent, and keep 301 redirects for at least a year.
Agree a forecast range for the post-launch dip with finance in advance, and judge recovery by page type against the baseline rather than by site-wide traffic.

A platform move is usually justified on cost, speed or features, and judged a month later on revenue. When organic traffic drops after launch, the new platform is rarely the cause. URLs changed without redirects, templates lost content, or filters created thousands of pages nobody planned for. Website migration SEO is the work that prevents those problems.

This article sets out the SEO side of replatforming, whether you are moving from Magento or Adobe Commerce to Shopify, from one enterprise platform to another, or to a headless front end. It covers what to do before, during and after launch, what normal looks like in the weeks afterwards, and what to ask before you sign off a go-live date.

What a platform move puts at risk

A migration touches every signal that earned your organic revenue: URLs, internal links, page content, structured data and site speed. Google tells site owners to expect temporary fluctuation in rankings during a move, and says that for a medium-sized site it can take a few weeks or more before the new URLs replace the old ones in results. Larger sites take longer.

Temporary fluctuation is manageable when it is planned for. Lasting loss usually comes from avoidable errors, and its cost runs well beyond SEO: paid search budgets rise to cover the gap, trading plans miss, and the platform project is remembered as the reason. The aim is a move where the dip is short, explainable and forecast in advance.

Platform constraints to plan for

Each platform shapes URLs differently, and that decides how much redirect work there is.

Shopify: product and collection URLs follow fixed paths, so a Magento URL such as /red-midi-dress.html becomes /products/red-midi-dress. Shopify's documentation says you can only redirect from broken URLs, lists reserved paths such as /products and /collections that cannot be redirected, and allows up to 100,000 redirects on standard plans and 20,000,000 on Plus.
Adobe Commerce (Magento): you set the URL suffix, such as .html, and whether product URLs include the category path. Adobe says that by default Commerce does not include the category path in product URLs, but older stores often run customised settings and years of accumulated URL rewrites, so crawl the live site rather than assuming.
Headless: URL handling, redirects, rendering, canonical tags and sitemaps sit with your developers, and nothing happens by default, so each needs a written requirement. Google recommends permanent server-side redirects and warns that it might never see a JavaScript redirect if rendering fails.

Faceted navigation needs the same attention. Filter URLs on the old platform may be indexed and earning traffic, while the new platform may generate them differently or not at all. On Shopify, URLs that use collection tag filtering cannot be redirected, so those decisions have to be made before launch. Decide which filtered pages deserve to exist as indexable category pages, and keep the rest out of the crawl, as Google's guidance on faceted navigation recommends.

Our website migration SEO plan, step by step

Most of the work happens in the months before launch, while URL rules and templates are still being decided. This is the sequence we follow.

Baseline everything before anything changes. We export a full crawl of the current site, at least twelve months of Search Console clicks and impressions by URL, organic revenue by landing page, the URLs that external links point to, and server logs where available. This record is what you will compare against, and it cannot be recreated once the old site is gone.
Rank URLs by value. On most catalogues we audit, a minority of pages earns most of the organic revenue. We sort every URL by revenue, clicks and inbound links so the mapping and testing effort goes where the money is.
Map every old URL to its closest new equivalent: product to product, category to category, guide to guide. Where a product has gone, redirect to the nearest replacement or parent category rather than the homepage. Google's site move guidance asks for images and other resources to be mapped too, not only pages.
Implement 301 redirects as single hops. Each old URL should go straight to its final destination, and redirects left over from earlier migrations should be updated to point at the new URLs directly. Google recommends permanent redirects such as 301 or 308, kept for as long as possible and generally for at least a year.
Protect content and metadata parity. Titles, meta descriptions, headings, category copy, product descriptions, reviews and FAQs should carry across template by template. We compare old and new crawls page type by page type, because a template that drops the category introduction drops it on every category at once.
Rebuild structured data and internal links. Product, offer, review and breadcrumb markup needs re-implementing and validating on the new templates; our guide to product pages and schema for AI answers covers the markup worth keeping. Navigation, breadcrumbs and in-content links should point at final URLs, not old ones that then redirect.
Test on staging, and keep staging out of the index. We crawl staging against the mapping file, test redirects for the highest-value URLs, and check canonical tags, robots.txt, noindex directives, hreflang and page speed. Staging should sit behind a password so it is never indexed.
Launch with a checklist and the right people on call. Switch redirects on, remove any staging blocks from the live robots.txt, and submit the new XML sitemap in Search Console while keeping the old one available so Google can see the redirects. Then crawl the old URL list to confirm every redirect resolves, and check that analytics and conversion tracking fire on the new templates.

If you trade in several countries, hreflang annotations have to be rebuilt with the new URLs; our guide to international e-commerce SEO and hreflang covers the detail. If the domain changes as well as the platform, Search Console's Change of Address tool also applies. It is for domain-level moves only, so a platform change on the same domain does not use it.

After launch: monitoring and what normal looks like

For the first two weeks we check daily: 404s and crawl errors in Search Console, redirect responses for the top URLs, indexing of the new URLs, organic sessions and revenue by page type against the baseline, and server response times. After that, weekly for at least three months.

Normal looks like this: some volatility in the first weeks, old URLs dropping out of the index as new ones replace them, and traffic to priority pages moving back towards the baseline as Google processes the redirects. There is no reliable standard recovery percentage or timeline, so we forecast a range for each move based on its size and how much changed, and agree that range with finance before launch.

Warning signs look different from normal volatility: one page type losing traffic while others hold, sustained 404s on URLs that used to earn revenue, or new URLs still not indexed weeks after launch. Each points to a specific fault that can be fixed, which is why the baseline by page type matters.

What to report upwards

Organic revenue and sessions by page type, against the pre-launch baseline and the agreed forecast range.
The share of priority URLs redirecting correctly and indexed at their new address.
Non-branded clicks from Search Console, which strip out brand demand that would have arrived anyway.
Open issues, with owners and fix dates.

When the timing is wrong, and the mistakes we see

Launching close to peak trading. A migration in the weeks before Black Friday or your main season leaves no room to recover. Move in a quieter period and freeze other site changes around launch.
Changing everything at once. A new platform, URL structure, design, domain and copy in one release makes faults hard to diagnose. Google notes that large sites can move one section at a time, which makes problems easier to find and fix.
Redirecting old URLs to the homepage or top-level categories, which throws away the relevance those URLs had built.
Removing redirects a few months after launch, often in a later clean-up.
Letting the new platform's default filters create indexable pages at scale.
Treating SEO as a launch-week task rather than a requirement from the first scoping meeting.

Questions to ask your team or agency

Do we have a full URL baseline, with revenue by landing page, stored somewhere that will outlive the old platform?
Who owns the redirect map, and how was it tested before launch?
Which templates lose any content, markup or internal links compared with today?
What dip are we forecasting, for how long, and what would trigger an emergency fix or rollback?
Is the launch date clear of our main trading periods?

Our e-commerce visibility playbook shows how a migration fits into a retailer's wider search plan, and the playbooks for fashion e-commerce and travel and hospitality cover sector issues such as seasonal ranges and inventory that changes daily. We plan and run migrations as part of our organic search work.

Frequently asked questions

How long does SEO take to recover after a website migration?

There is no standard timeline. Google says that for a medium-sized site it can take a few weeks or more for the new URLs to replace the old ones in results, that larger sites take longer, and that rankings fluctuate temporarily during a move. Recovery depends on the size of the site, how much changed and whether redirects, content and internal links were carried across correctly.

How long should you keep redirects after a site migration?

Google recommends keeping redirects for as long as possible, and generally for at least one year, and suggests considering keeping them indefinitely for users who follow old links. It recommends permanent server-side redirects such as 301 or 308, pointing straight to the final URL without chains. Removing redirects early risks losing the links and rankings the old URLs had earned.

Can you keep your URLs when moving from Magento to Shopify?

Usually not for products and categories. Shopify uses fixed paths, so products sit under /products/ and categories under /collections/, while Magento and Adobe Commerce URLs often use a .html suffix and sometimes a category path. Every changed URL needs a 301 redirect to its closest equivalent, set up through Shopify's URL redirects, which only apply to URLs that no longer exist.

What should an SEO site migration checklist include?

A full baseline of URLs, clicks and organic revenue; a map of every valuable old URL to its new equivalent; single-hop 301 redirects; parity checks on titles, content and structured data; updated internal links, canonicals, hreflang and robots.txt; a staging crawl; launch-day redirect and tracking checks; a new XML sitemap in Search Console; and daily monitoring by page type for the first weeks after launch.