Replatforming is the single most dangerous thing a store can do to its organic traffic. It is also often necessary. The businesses that come through it intact are the ones that did the boring preparation, and the ones that lose half their traffic almost always skipped the same four steps.
Before the launch date is set
Record where you stand. Export twelve months of Search Console data: every URL with its impressions and clicks. Export your rankings for every tracked term. Export your top pages from Analytics. You cannot tell whether a migration went badly if you never wrote down what normal looked like.
Crawl the current site completely. Every URL, every status code, every redirect that already exists. This is your source list for the redirect map.
Export your backlinks. You need to know which pages have earned links, because those are the URLs that absolutely must resolve after launch.
Build the redirect map
This is where migrations are won or lost.
Every old URL needs a new destination. Not most of them. Every one that had traffic, had links, or was indexed.
Rules:
- Map to the closest equivalent page, not to the home page or a catch-all category.
- Use 301, not 302.
- Avoid chains. Old URL to new URL, one hop. If your site already has redirects from a previous migration, flatten them so the old one points directly at the new destination rather than through the intermediate.
- Test the map on staging before launch, not after.
If the platform forces a URL structure change, for example Shopify's /collections/ and /products/ prefixes, your map has to cover the whole catalogue. Do not launch with a partial map and a plan to finish it later.
Match the content
Page titles, meta descriptions, H1s, body copy, image alt text and schema all need to carry across. New themes love to swap the H1 for the store name, drop the collection description, or strip the structured data out entirely.
Crawl staging and compare it against your crawl of the live site. Any page where the title or H1 changed unintentionally is a flag.
Check staging is not indexable
Staging sites get indexed constantly. Put HTTP authentication on it, not just a noindex tag. A noindex that someone forgets to remove at launch costs you the whole site.
Then, on launch day, check that the noindex is gone from production. This is the most embarrassing way to lose a migration and it happens regularly.
Launch day
In this order:
- Redirects live from minute one, not the day after.
- Verify the new site in Search Console if the domain changed, and submit the change of address.
- Submit the new sitemap.
- Crawl the live site immediately and check status codes.
- Spot check twenty of your highest traffic URLs by hand.
The first eight weeks
Watch, do not panic. A dip of ten to twenty per cent for two to four weeks is normal even on a clean migration. Google needs to recrawl and reprocess the whole site.
Check weekly:
- Search Console coverage for new errors
- The Crawl Stats report for 404 spikes
- Your highest traffic URLs, by hand
- Core Web Vitals, because new themes are often slower
If traffic has not recovered by week eight, something is broken rather than settling. The usual culprits are missing redirects, a lost noindex, changed internal linking, or canonical tags pointing at the old domain.
The mistake nobody expects
Internal links. Old sites accumulate contextual links between pages over years. A new theme with a clean template often drops most of them, and pages that were held up by internal linking quietly fall.
Compare the internal link counts from your before and after crawls. If a page went from forty inbound internal links to two, that is why it dropped.
We handle migrations as part of technical SEO, usually alongside WordPress development or an e-commerce replatform. The technical SEO checklist covers what we check on any site, migration or not.