Platform migrations are where ecommerce businesses go to lose a year's worth of SEO in a weekend. The new site looks better, loads faster, and the team is proud — and organic traffic falls off a cliff because nobody mapped the redirects, the URL structure changed silently, and Google is now crawling a maze of 404s. Every part of that is preventable. A migration done properly is invisible to customers and to Google; a migration done carelessly is the most expensive project you'll ever "save money" on.
This is the comprehensive checklist we work from when moving UK ecommerce stores between platforms — Shopify to WooCommerce, Magento to Shopify, custom builds to anything, and everything in between. Follow it in order: before, during, and after launch.
Phase 1: Audit and inventory (4–8 weeks before launch)
You can't protect what you haven't mapped. Start with a full crawl of the existing site and export everything: every URL, its status code, its traffic (last 12 months from analytics — a full year captures seasonality), its backlinks, and its revenue attribution. Identify your most valuable pages: top traffic pages, top revenue pages, pages with external backlinks, and pages ranking in the top 20. These get white-glove treatment — everything else gets the standard process, but nothing gets forgotten.
Inventory the invisible stuff too: XML sitemaps, robots.txt rules, hreflang setup, structured data, custom tracking (enhanced ecommerce events, goals, pixels), integrations (payment gateways, ERP, email platform, reviews provider, live chat), and content that lives outside the product catalogue — blog posts, buying guides, landing pages. Migrations fail most often on the things nobody wrote down. Also benchmark everything now: organic traffic, revenue, conversion rate, average page speed, index coverage in Search Console. Without baselines, you can't tell whether the migration hurt you or the algorithm just had a bad week.
Phase 2: URL mapping and redirect planning
This is the heart of the migration. Build the complete redirect map: every old URL to its new equivalent, one by one. Category to category, product to product, blog post to blog post. Where there's no equivalent, redirect to the nearest sensible parent (a discontinued product goes to its category, not the homepage — mass redirects to the homepage read as soft 404s and leak authority). Use 301 permanent redirects, implemented server-side, and test every single one before launch — not a sample, every one. A spreadsheet with 4,000 rows is tedious; a 404 on your bestselling product page is expensive.
Decide the URL structure deliberately. Keep URLs as close to the old structure as possible unless the old structure was broken — change the platform, not the URLs, in one move if you can. If the new platform forces structural changes (it often does — Shopify's /products/ and /collections/ prefixes, for example), that's fine, but it's exactly why the redirect map exists. Also plan for URL parameters: filtered navigation, sorting, and internal search must not create indexable duplicate URLs on the new platform. Set canonicals and noindex rules before launch, not after you notice the index bloating.
Phase 3: Technical build checks
Before the new site goes live, verify the technical SEO foundation on staging (blocked from search engines, but otherwise fully testable). Crawl the staging site and compare against the old: same page count in the same places, no orphan pages, no unexpected noindex tags (staging "don't index" settings left on at launch is a classic disaster — check it twice). Confirm page speed on the new platform with real product pages, not just the homepage; a theme that's fast on a demo with twelve products can crawl with twelve thousand.
Check structured data renders correctly, hreflang is in place if you sell internationally, the XML sitemap generates and includes the right URLs, and robots.txt allows crawling of what matters. Migrate tracking deliberately: analytics, Search Console, ad pixels, affiliate tracking — verify each fires on the new site. And sort hosting and SSL: the new site must be fully HTTPS with no mixed-content warnings, and the hosting must handle your peak traffic, not your average Tuesday. If technical SEO isn't your team's strength, this is the highest-value place to bring in specialists — our technical SEO team does pre-launch migration audits for exactly this reason.
Phase 4: Content and data migration
Product data rarely moves cleanly between platforms. Fields don't line up, image filenames change, descriptions get truncated, variants restructure. Plan the data mapping field by field, migrate a sample, and inspect it by hand before running the full import. Images deserve special attention: migrate alt text with the images (it's SEO equity and accessibility), keep filenames sensible, and don't let the new platform serve every image at full resolution — compress and use modern formats.
Content is the other casualty. Category descriptions, buying guides, blog posts — migrate all of it, with internal links updated to the new URLs (not left pointing at old URLs that now redirect; redirect chains dilute authority and slow crawling). Customer accounts, order history, and reviews need a migration plan too — losing years of product reviews tanks conversion on day one. And if you're changing design, keep the content that earned rankings: rewriting every category description during a migration means changing two variables at once, and you'll never know which one caused the traffic change.
Phase 5: Launch day protocol
Launch on a Tuesday, Wednesday, or Thursday morning — never Friday, never before a peak period. Have the redirect map deployed and tested, Search Console and analytics verified on the new property, and the old site's Search Console property kept for comparison. Monitor in real time: crawl the live site immediately for 404s and redirect chains, watch Search Console's coverage report daily for the first two weeks, and track revenue and conversion hourly on day one — traffic dips are expected and recoverable, revenue anomalies need instant investigation.
Expect a traffic dip. Even a perfect migration typically sees 2–4 weeks of fluctuation as Google recrawls and reassigns authority; a 10–20% temporary dip is normal, and recovery to baseline (then growth) over 4–8 weeks is the healthy pattern. What's not normal: a 50%+ drop that doesn't start recovering within two weeks — that's a signal something structural broke, and it needs diagnosing immediately, not "after the quarter."
Phase 6: Post-launch (the first 90 days)
The migration isn't done at launch — it's done when the metrics stabilise. Keep the old domain's redirects live for at least a year (longer if backlinks point at old URLs). Run weekly crawls comparing old URL list against new status codes — redirect chains and 404s creep in as content gets edited. Re-submit sitemaps, monitor index coverage until it matches the old baseline, and watch rankings for your top 100 keywords specifically, not just aggregate traffic.
Do a proper retrospective at 90 days: what broke, what the baselines say, what you'd do differently. Feed it into the runbook for next time. And resist the urge to start "improving" SEO aggressively in the first month — changing content and structure while Google is still processing the migration muddies every signal. Stabilise first, optimise second. For the longer game of growing the new store, our guide to mastering ecommerce SEO picks up where this checklist leaves off.
FAQs
How long does an ecommerce migration take?
The technical build varies by platform and catalogue size, but the SEO-safe process around it needs 4–8 weeks of preparation before launch and 90 days of monitoring after. Anyone proposing to migrate a serious store over a weekend is describing the file transfer, not the migration. The redirect mapping and testing alone take weeks on a large catalogue.
Will I definitely lose traffic when migrating?
A small, temporary dip is normal even when everything is done right — Google needs time to recrawl and reassign authority. Permanent losses come from specific failures: missing redirects, changed URLs without mapping, lost content, broken structured data, or staging noindex left on. The checklist above exists to eliminate every one of those.
Should I redesign at the same time as migrating platforms?
Ideally, no. Changing platform and design simultaneously means two major variables change at once, and if traffic drops you can't isolate the cause. If the business needs both, sequence them: migrate first, stabilise, then redesign — or redesign first on the old platform. Reality sometimes forces a combined project; if so, keep URLs and content as stable as possible and change only the presentation.
What happens to my Google rankings during migration?
With proper 301 redirects, rankings transfer — Google has confirmed redirects pass ranking signals. Expect fluctuation for a few weeks while the new URLs are recrawled and re-evaluated. Pages may dance in the rankings before settling, usually at or near their old positions. Persistent drops point to a technical failure, not a Google punishment.
Can I migrate from Magento to Shopify without losing SEO?
Yes — it's one of the most common migrations we see, and it goes well when the redirect map is complete, URL changes are deliberate, content migrates intact, and speed actually improves (a common win, since bloated Magento builds are often slow). The platform doesn't determine the SEO outcome; the process does.
A seamless migration is 90% preparation and 10% launch day. If you're planning a move and want a second pair of eyes on the redirect map, the staging crawl, or the whole plan, talk to us before you commit to a date — the cheapest migration problems are the ones caught in planning.
