SITE MIGRATION CHECKLIST. How to migrate a website without losing traffic

Why do you need a site migration checklist

Site migration is one of the highest-risk SEO operations.

A single mistake during migration can:

• wipe out years of organic traffic,
• break indexation across thousands of pages,
• silently waste crawl budget,
• and only become visible weeks after launch, when rankings are already gone.

If you’ve never done a site migration before, this checklist exists to answer one simple question:
What exactly do I need to do to migrate a site without losing traffic?

This is not an article and not theory.
This is a step-by-step checklist you can follow before, during and after a site migration.

What this checklist helps you avoid

Before migrations, most teams operate under two dangerous assumptions:

1. “We’ll catch issues after launch”
   → By then, traffic is already lost.
2. “Search engines will figure it out”
   → Bots don’t fix broken canonicals, redirects, or rendering issues.

This checklist helps you:

• see what search bots actually crawl,
• validate critical elements before launch,
• detect issues early instead of reacting to damage,
• and keep traffic stable throughout the migration.

How to use this checklist

• Follow the steps in order
• Do not skip steps, even if they feel “minor”
• Use it as a validation framework, not just a to-do list

You don’t need prior migration experience – this checklist is designed to guide you through the process.

Now follow the checklist below step by step. Do not skip steps.

SITE MIGRATION CHECKLIST

Phase 1 – Pre-Migration Preparation

1. Define Migration Goals

• Improve UX, speed, scalability
• Increase conversions, reduce server load
• Align product roadmap with modern architecture

2. Select JavaScript Framework & Rendering Strategy

• Choose framework supported by search engines
• Decide between SSR, CSR, Dynamic Rendering
• Confirm long-term support of framework version
• Plan SSR architecture early (not after launch)

3. Prepare Staging Environment for SEO Testing

• Staging must be crawlable (password optional)
• SSR must be enabled
• DevTools tests for HTML, SSR, and JS versions
• Chrome DevTools / Postman testing with Googlebot user agent

Phase 2 – Prepare for Real Users (A/B Testing)

4. Launch A/B Test – Start With a Small Percentage

• Start with 1% of users (large sites) or 10% (small sites)
• Compare conversion rate
• Compare bounce rate
• Compare cart additions & checkout funnel
• Identify UI/UX bugs

5. Fix All User-Facing Issues Before SEO Testing

• Cart issues
• Payment failures
• Slow SSRRendering glitches
• Lazy loading edge caseserstanding your real visibility across the entire search ecosystem.

6. Keep JavaScript Version Hidden From Search Engines (During A/B Tests)

This step applies ONLY during user A/B testing phase – before opening JS version to search engines

• Search engines (Googlebot, Bingbot, etc.) see only the old HTML version
• The JS version is shown only to real users participating in A/B tests
• Proxy / server rules detect bots by User-Agent and/or IP and always return the HTML version
• Checked in GSC Live Test and logs that Googlebot does not receive the JS version during A/B tests

Phase 3 – Prepare for Search Engines

7. Prepare a Test Pool of URLs

• Product pages
• Category pages
• Filter pages
• Blog/articles
• Static content pages

Rules:

• Choose URLs frequently crawled by Google
• Do NOT choose top-traffic URLs
• Create segments based on page templates

8. Collect Baseline Data (Before Migration)

Collect at least 4–12 weeks of data:

• Positions
• Clicks
• Impressions
• CTR of ranking keywords per URL
• Organic conversions
• Crawl frequency
• Status codes
• Server load
• Core Web Vitals
• Logs (bot activity patterns)

9. Create Monitoring Dashboards

• Use tools (e.g., JetOctopus, GSC, GA4):
• HTML vs JS comparison dashboard
• Rendering performance dashboard
• SSR availability alerts
• Log anomalies
• Indexation changes
• Content changes (titles/meta/H1)

Phase 4 – Enable JavaScript for Search Engines (Limited Test)

10. Allow Googlebot to Access Only Test URLs

• Open a small test set
• Block all other URLs
• Maintain strict proxy settings

11. Monitor Rendering & Indexing

Check:

• SSR HTML vs rendered DOM
• Canonicals
• Meta robots tags
• Hreflang
• Structured data
• Internal links
• Missing content
• JS errors
• Added/removed text
• Page size changes
• Load time after JS execution

12. Monitor Bot Behavior

Use logs to verify:

• Crawl frequency spike is normal
• No server overload
• Status codes stable
• No redirect loops
• No blocked JS resources

13. Compare Before/After Performance

Check for each test page:

• Positions
• Clicks & impressions
• CTR
• Keywords count
• Rendering time
• Indexation status

Phase 5 – Full Migration Ready Checklist

Your site is ready ONLY if all points below are TRUE:

14. User Metrics

• No sharp drop in conversions compared to the HTML baseline
• No checkout or cart bugs
• Performance is stable

15. SEO Technical State 

• SSR works for every template
• Metadata is correct on both SSR & JS
• The following key elements are present and consistent in SSR HTML and rendered JS:
  – <title>
  – meta description
  – meta robots 
  – canonical, hreflang (if used)
  _ <h1>
  – main content / key product information
  – internal links (navigation, breadcrumbs, related items)
  – structured data
• Page returns the correct status code
• CWV are stable (especially LCP, INP and CLS)
  
  16. Search Engine Test Results
  
• Test pages did not lose rankings
• Indexation is correct
• Googlebot crawls efficiently
• Rendering is successful
• No major JS errors
• Logs show typical behavior

If all checks are green → you’re ready!

Phase 6 – Controlled Full Migration

17. Migrate in Stages

Recommended order:

• 1st: low-traffic subdomain
• 2nd: medium-traffic sections
• 3rd: final migration of main domain

18. Continue Daily Monitoring

• SSR tests after each release
• Rendering tests
• GSC positions
• Logs anomalies
• Content changes
• Crawl frequency
• Indexation status

19. Have a Rollback Plan

• Instant rollback to previous version
• Revert SSR or proxy rules
• Freeze deployments
• Alert devops + SEO team

Phase 7 – Post-Migration Stabilization

20. Weekly Audit

• Crawl entire site with JS enabled
• Compare HTML vs JS changes
• Identify missing elements
• Detect template issues
• Monitor indexing & rankings

21. Monthly Audit

• Full performance analysis
• Log analysis
• GSC trends report
• Identify long-term JS errors
• Review Core Web Vitals

22. Continue Improving JS SEO

• Reduce JS execution time
• Optimize SSR
• Minify JS bundles
• Reduce unused JS
• Improve lazy loading
• Optimize content loading paths

🎉 Congratulations – You Are Ready to Migrate to JavaScript Safely

From checklist to confidence

This checklist helps you structure a safe site migration.
But confidence comes from validation – not assumptions.

If you’d like expert validation of your site migration plan or help reviewing critical steps from this checklist, book a migration consultation with our team.