Zero-Loss Website Migrations: Replatform, Redesign, Move Domains
Written by on Friday, August 15th, 2025
The Website Migration Handbook: Replatforms, Redesigns, and Domain Moves Without Losing SEO or Revenue
Website migrations are high-stakes projects that can unlock growth—or erase hard-won visibility and sales. Whether you’re swapping platforms, changing your information architecture, or moving to a new domain, the playbook is the same: reduce variables, protect what works, and make it easy for users and search engines to follow the change. This handbook outlines the end-to-end approach, from planning to post-launch monitoring, so you can evolve your site without sacrificing SEO or revenue.
Understand the Migration Types and Risk Profile
- Replatform: Moving from one CMS/ecommerce platform to another (e.g., Magento to Shopify Plus). Risks include URL changes, template differences, and feature parity gaps.
- Redesign/IA change: New templates, layout, and navigation. Risks involve content shifts, internal link changes, and above-the-fold content that alters perceived relevance.
- Domain move: Changing the root domain or subdomain strategy. Highest risk; requires redirects, Search Console updates, and re-verification across tools.
- Protocol/host changes: HTTP to HTTPS, www to non-www, or CDN subdomain adjustments. Usually lower risk if redirect and canonicalization are precise.
Stacking changes (e.g., replatform + redesign + domain move) compounds risk. When possible, stage them: stabilize URLs and tech first, then update design.
Pre-Migration Strategy: Goals, Inventory, and Benchmarks
- Define KPIs: Non-brand organic sessions, revenue/conversions, rankings for priority keywords, crawl errors, Core Web Vitals, and page index counts.
- Create a full inventory: Export all URLs (live, in sitemaps, ranking URLs) with traffic, backlinks, and revenue. Include PDFs, images, video pages, and parameterized URLs.
- Map intent and value: Identify pages that drive most traffic/revenue and pages with strong backlinks. These require extra care.
- Baseline data: Capture Search Console exports, analytics, server logs (last 30–90 days), and top landing pages. Screenshot key reports for post-launch comparison.
- Define OK-to-retire content: Plan 410 (Gone) for content with no value, and consolidations for cannibalized pages, with redirects to the best target.
URL Mapping and Redirect Architecture
Redirects are the spine of your migration. Get them wrong, and users and bots get lost.
- One-to-one mapping: For every legacy URL, define the exact new destination. Avoid redirect chains and loops.
- Use 301s for permanent moves: 302s and meta refreshes can erode equity and confuse bots.
- Normalize rules: Enforce a single canonical host (www vs non-www), HTTPS, lowercase, trailing slash policy, and remove junk query parameters.
- Dynamic patterns: Use rewrite rules for large catalogs, but verify edge cases manually for top-value URLs.
- Test before launch: Validate redirect maps with a crawler on a staging host, using host rewrites to simulate production.
- Custom 404: Provide helpful navigation, search, and popular links. Log all 404s with referrer to inform patches post-launch.
Technical SEO Parity Checklist
Crawlability and Indexation
- Ensure robots.txt allows essential sections; remove staging disallows before launch.
- Meta robots parity: pages indexable before should remain indexable unless intentionally changed.
- XML sitemaps: generate fresh sitemaps with new URLs; submit in Search Console and robots.txt.
Canonicalization and Internationalization
- Self-referencing canonical tags on indexable pages; no cross-domain canonicals during a domain move unless reflecting the new domain.
- hreflang tags updated for each locale, with correct return tags and consistent regional mapping (e.g., en-US vs en-GB).
Structured Data
- Replicate schema markup (Product, Article, Organization, Breadcrumb, FAQ) with identical or improved attributes.
- Validate with Rich Results Test; avoid structured data that doesn’t match visible content.
Internal Linking and Navigation
- Preserve internal links to high-value pages; ensure no orphaned pages.
- Use descriptive anchor text; avoid JavaScript-only navigation that hides links from crawlers.
Performance and Core Web Vitals
- Set performance budgets (e.g., TTFB < 200ms, LCP < 2.5s, CLS < 0.1, INP < 200ms).
- Use HTTP/2 or HTTP/3, Brotli compression, critical CSS, image optimization (WebP/AVIF), and lazy loading.
- Audit third-party scripts; load non-critical tags after interaction or with defer.
Media and File Hygiene
- Preserve image URLs where possible; otherwise redirect and update sitemaps.
- Include alt text, dimensions, and responsive srcset.
- Keep downloads (PDFs) mapped; set correct cache headers and content types.
Content and Design Changes Without Losing Relevance
- Maintain content parity: Preserve on-page copy, headings, and schema for pages tied to rankings. If you must rewrite, do it post-migration with measurement.
- Above-the-fold signals: Keep core keywords in H1, intro paragraphs, and title tags; avoid moving primary content below expandable tabs.
- Navigation IA: Ensure important categories remain one to two clicks from the homepage; maintain breadcrumbs for context and internal link equity.
- UX experiments: Use feature flags to roll out new components. Avoid heavy A/B testing scripts at launch that can create cloaking-like behavior.
Analytics, Tags, and Revenue Tracking
- Audit all tracking: GA4, server-side tagging, pixels (Meta, TikTok), heatmaps, and consent tools. Migrate GTM containers carefully.
- Verify ecommerce events: view_item, add_to_cart, begin_checkout, purchase—match previous parameters (currency, item IDs, coupon codes).
- Maintain UTM conventions and update internal links and emails to new URLs.
- Coordinate paid media: update final URLs, sitelinks, Shopping feeds, and verify Merchant Center/ads domain claims.
- Set up annotations and alerts for traffic, conversion drops, and 5xx spikes.
Infrastructure and DNS: Minimizing Downtime
- Prepare SSL/TLS certificates and HSTS configuration in advance; preload only after stability.
- Set DNS TTL to a low value (e.g., 300 seconds) 24–48 hours before cutover to enable quick propagation.
- Use a CDN with origin shielding and caching rules; warm caches for top pages before launch.
- Ensure canonical host redirects at the edge; avoid mixed-content errors and duplicate HTTP/HTTPS versions.
Staging, QA, and Launch Plan
- Secure staging with auth/whitelisting; block indexing with robots.txt and x-robots noindex. Remove all blocks at go-live.
- QA checklist: titles/meta, headings, canonicals, structured data, internal links, pagination rel tags, faceted navigation rules, and robots directives.
- Run a full crawl of staging, compare to production inventory, and fix mismatches before launch.
- Prepare rollback: keep legacy environment live and switchable; maintain a revert strategy for critical issues.
Rollout Strategies: Big-Bang vs. Phased
- Big-bang: Entire site switches at once. Works when mapping is precise and time windows are predictable. Ensure 24/7 monitoring.
- Phased: Migrate section by section or use traffic splitting. Reduces risk but complicates analytics and cross-domain cookies.
- Feature flags: Toggle templates or modules; enable testing with a small percent of users before full release.
Post-Launch Monitoring and Troubleshooting
- Submit new sitemaps; for domain moves, use Search Console’s Change of Address tool and re-verify properties.
- Track coverage, crawl stats, and Core Web Vitals in Search Console. Watch for spikes in 404s, soft 404s, and 5xx errors.
- Analyze server logs to ensure Googlebot/Bingbot are hitting 200s on key pages and that 301s are being crawled.
- Check rankings for top queries daily for 2–3 weeks; validate that landing pages remain relevant.
- Patch redirect gaps reported by logs, analytics, and customer support tickets.
- Compare revenue and conversion rate by device and channel; investigate anomalies at template or payment-step level.
Real-World Examples
Ecommerce Replatform: Magento to Shopify Plus
A multi-brand retailer migrated 25,000 SKUs and changed product URL patterns. They built a rule-based 301 map and manually curated the top 2,000 product and category redirects by revenue. They replicated Product schema, reviews, and maintained identical titles/descriptions for top landing pages. By pre-warming the CDN and delaying design changes for 30 days post-launch, they saw a two-week dip in long-tail product queries but returned to baseline in week three, with a 9% improvement in LCP improving conversion rate by 4%.
News Site Redesign
A publisher shifted to a modern layout with infinite scroll. Early tests showed that related article links were hidden behind JS events, reducing internal link discovery. They reintroduced visible “Most Read” modules and server-rendered pagination. Combined with preserving Article schema and author pages, organic sessions remained stable and pages per session increased by 12%.
B2B SaaS Domain Move After Rebrand
The company moved from exampleapp.io to example.com and consolidated a blog subdomain. They executed a strict www + HTTPS policy, used Change of Address in Search Console, and pushed a PR/partner campaign to refresh backlinks to the new domain. With a complete redirect map and identical content, branded rankings updated within days, and non-brand queries normalized within four weeks. Leads dipped 6% in week one, then surpassed baseline by week five as old links were updated.
Common Pitfalls and How to Avoid Them
- Blocking bots on launch: Staging robots.txt or noindex tags accidentally left in place. Automate a pre-flight check that fails deployment if present.
- Redirect chains: Legacy redirects colliding with new rules. Flatten before launch and test top 10,000 URLs.
- Soft 404s: Redirecting many old pages to the homepage. Map to the closest relevant page or return 410.
- Parameter chaos: Losing tracking or creating duplicate content with parameters. Define a parameter handling policy and canonicalization.
- Tag manager drift: Missing or duplicate tags inflating metrics. Version-control containers and peer review changes.
- Overhauling content all at once: Major copy changes combined with a platform switch obscure causality. Stagger edits and measure impact.
Migration Timeline Template
- T-8 to T-6 weeks: Define KPIs and scope; complete URL inventory and prioritization; draft redirect map; performance budget set; tracking audit.
- T-6 to T-4 weeks: Implement redirects in staging; replicate metadata, schema, and content; IA and internal linking finalized; start paid media coordination.
- T-4 to T-2 weeks: Staging crawl and parity checks; structured data validation; CDN and cache rules; DNS TTL lowered; QA payment flows and forms.
- T-1 week: Final redirect testing on top pages; sitemap generation; analytics and pixels verified; rollback and comms plan rehearsed.
- Launch day: Deploy code and redirects; switch DNS; verify SSL/HSTS; remove noindex; submit sitemaps; monitor logs, 404s, 5xx, and key KPIs hourly.
- Week 1–2: Patch redirect gaps; monitor Search Console coverage and crawl stats; check rankings for priority terms; validate revenue tracking and UX.
- Week 3–6: Outreach to update important backlinks; begin post-migration enhancements (design iterations, content refreshes) with controlled tests.
Governance and Roles
- Establish a RACI: SEO lead (redirects, parity), Dev lead (infrastructure, templates), Analytics lead (tracking), PM (timeline, comms), Marketing (PR, PPC), Support (issue intake).
- Create a shared war room channel with real-time dashboards and an issue tracker tagged by severity and owner.