A replatform is the single most dangerous thing you can do to your organic traffic. Every product URL, every collection, every blog post gets a new address, and every link pointing at the old one now leads nowhere.
The traffic loss does not appear immediately, which is what makes it so damaging. By the time rankings visibly drop, the cause is weeks behind you.
Crawl before you cut over
You cannot redirect URLs you have not enumerated. Before DNS changes, crawl the existing site and export every indexed URL — products, collections, pages, blog posts, filtered and paginated variants.
Pull the top landing pages from Search Console and analytics as well. A crawl finds what exists; those reports tell you what actually earns traffic, and that is the list you cannot afford to get wrong.
Map old to new, explicitly
Every old URL needs a destination that returns 200. Redirecting everything to the homepage is the classic mistake — search engines treat a mass redirect to the root as a soft 404 and the equity evaporates anyway.
Where a product no longer exists, send it to the closest equivalent or its collection. The rule is relevance: the destination should satisfy the intent that earned the original ranking.
Use 301, never 302
A 301 says the move is permanent and passes ranking signals to the new URL. A 302 says it is temporary and does not.
This distinction costs nothing to get right and is expensive to get wrong, because the damage is invisible until traffic has already gone.
Handle families of URLs with patterns
Migrations rarely break ten URLs. They break hundreds, usually in structural groups — an entire old category path, or a URL format that no longer exists.
Pattern-based rules let one entry catch a whole shape of URL. It is the difference between an afternoon of work and a fortnight of it, and it means fewer hand-typed mistakes.
Verify after cutover, not before
Once live, test the top URLs directly. Each should return a single 301 to a live 200 — no chains, no loops, no redirect that lands on another redirect.
Then watch 404s for the following weeks. Real traffic finds URLs your crawl missed, especially from old emails and external links, and those are worth mapping as they appear.
- Every old URL returns one 301 to a live page
- No redirect chains
- Sitemap submitted with new URLs only
- 404 report reviewed weekly for the first month
The outcome
The rankings and backlinks you spent years earning survive the move, instead of being rebuilt from zero.