How to change platform without losing your Google rankings
Migrations don't lose traffic because the data moved badly. They lose traffic because nobody wrote the redirect map. Here's the process that prevents it.
Every few weeks someone contacts us because their traffic fell off a cliff after a replatform. The store works, the products are all there, the design is better, and organic traffic is down 40% and not recovering.
It's almost never the data migration. It's the URLs.
Why every migration changes your URLs
Platforms impose their own URL structures. Shopify forces products to live under /products/ and categories under /collections/. WooCommerce lets you configure paths. Wix and Squarespace each have their own patterns.
So when you move, every single URL on your site changes. Every product, every category, every blog post, every page. And every one of those URLs may have accumulated years of Google's understanding, plus links from other sites pointing at it.
If a URL changes and nothing tells Google where it went, that page's accumulated authority doesn't transfer. It's simply gone.
What a 301 redirect actually does
A 301 is a permanent redirect. It tells browsers and search engines that a page has moved, and it passes the large majority of that page's ranking signals to the new location.
The important word is *permanent*. A 302 (temporary), does not reliably pass authority, and using one by mistake is a common and expensive error.
Redirects need to be live at the moment of launch, not added a week later once someone notices. In that gap Google crawls dead URLs, starts dropping them, and you spend months recovering ground you didn't need to lose.
The mistake that does the most damage
Redirecting everything to the homepage.
It's tempting, one rule, no mapping, no dead links. But Google treats a redirect to an irrelevant page as a soft 404, and passes essentially nothing. You get the appearance of having handled redirects while getting none of the benefit.
Each old URL needs to point at its closest genuine equivalent. A product to that product. A category to that category. A blog post to that post. Where there's truly no equivalent, the honest answer is a 410 telling Google it's gone deliberately.
The process that works
Inventory everything first. Crawl the existing site and list every URL. Then cross-reference against analytics and Search Console, because your crawl won't find pages that are orphaned but still ranking. Anything with traffic or backlinks goes on a must-preserve list.
Decide before you build. Every URL gets a decision: moves here, merges into that, or goes deliberately. Make those decisions while the design is still flexible, so a page bringing 300 visits a month doesn't get cut because it didn't fit a template.
Build the map as a document. A spreadsheet with old URL and new URL, reviewed by whoever knows the business. Not a rule someone writes on launch day.
Test the redirects before cutover. On staging, with the actual list. Check for chains (A to B to C), because each hop loses a little and slows things down.
Launch with them live. The redirects deploy with the site.
Then watch. Search Console's coverage report for four weeks minimum. New 404s appearing means you missed something, and finding it in week one costs almost nothing.
What to expect afterwards
Even a well-executed migration usually shows a dip. Google has to recrawl everything, follow the redirects and update its index, and that takes two to four weeks. A 10-20% wobble in that window is normal and not a sign of failure.
What isn't normal is a sustained drop that doesn't recover by week six. That means redirects are missing, wrong, or pointing at irrelevant pages, and it's fixable, but the longer it runs the more ground you give up.
The things that never transfer
Two, regardless of platform pair.
Passwords. They're hashed and not portable. Customers reset on first login, which needs an email prepared before launch rather than discovered by confused customers.
Subscriptions. Recurring payment authorisations are tied to your gateway and cannot be moved. Plans have to be rebuilt and customers re-authorised. Some churn is realistic, and if you run subscriptions this is the single biggest variable in your project.
One question to ask any agency
Before you sign a migration quote, ask how they'll handle redirects.
A specific answer (inventory, mapping, review, testing, monitoring), means they've done this before and lost sleep over it. Vagueness, or "we'll set up redirects", means it's an afterthought.
The data migration is the visible half of the job. The redirect map is the half that decides whether you keep what you spent years earning.
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