Most Next.js migrations go wrong in the same way: development teams focus on rebuilding functionality and assume SEO "will sort itself out". It doesn't. Schema breaks. Redirects have chains. Meta tags get wrong canonical URLs. Images lose alt text. And Google notices all of it within weeks of launch.
This checklist is built from analysis of dozens of Next.js migrations — the items on this list are the ones that actually cause rankings drops when missed.
Pre-Migration (Before Development)
- Export full sitemap from current site
- Crawl all URLs with Screaming Frog or Sitebulb
- Export Google Search Console URL performance data (12 months)
- Document all existing redirect rules
- Map all old URLs to new URL structure (redirect spreadsheet)
- Identify top-50 pages by impressions (protect these first)
- Export all meta titles and descriptions
- Export all schema markup JSON-LD
- Document internal link architecture
- Screenshot page layouts for QA reference
- Baseline Core Web Vitals scores (LCP, INP, CLS)
During Development
- Implement metadata per page using generateMetadata()
- Set canonical URLs for all pages
- Implement all redirects in next.config.js redirects array
- Add robots.txt with correct disallow rules
- Generate dynamic sitemap.xml
- Implement structured data (Article, Breadcrumb, Product schemas)
- Configure next/image for all images (width, height, alt text)
- Use next/font to prevent font layout shifts
- Implement hreflang tags for multilingual sites
- Set up Open Graph and Twitter Card tags
- Test noindex pages are correctly excluded
Pre-Launch QA
- Validate all redirects return 301 (not 302)
- Check redirect chains (max 1 hop)
- Test all schema with Google Rich Results Test
- Compare meta tags old vs new for top-50 pages
- Compare H-tag structure old vs new
- Check all images have alt text
- Validate robots.txt doesn't block Google
- Test sitemap.xml is accessible and accurate
- Run Lighthouse on top 10 pages
- Test mobile responsiveness on iOS and Android
- Check all forms and interactive elements work
- Validate 404 page returns correct 404 status code
Post-Launch (Week 1-4)
- Submit new sitemap in Google Search Console
- Request indexing for top-50 pages via URL Inspection
- Monitor GSC for crawl errors daily (first week)
- Monitor impressions/clicks in GSC vs baseline
- Set up Google Analytics 4 if not already done
- Check for soft 404s in GSC Coverage report
- Monitor Core Web Vitals in GSC real user data
- Check redirect mapping is working via bulk URL checker
- Monitor rankings for top-50 keywords weekly
- Fix any issues within 48 hours of discovery
- Document all post-launch changes made
- Conduct full re-crawl at 30 days post-launch
- Compare month-1 vs pre-migration GSC performance
The Most Critical Item: Redirect Mapping
If you only do one thing perfectly, make it the redirect map. Every old URL that existed and ranked needs a 301 redirect to its new equivalent. This is non-negotiable for preserving link equity. Use our Redirect Checker to validate every redirect returns a 301 (not 302) and has no redirect chains.
Validating Meta Tags & Schema at Scale
For large sites with hundreds of page templates, use our Meta Tag Comparison tool to spot-check key pages against their old equivalents. Use the Schema Validator to confirm structured data is rendering correctly in the HTML response (not just in JavaScript after execution).