Background
The client launched quickly with a React SPA and kept adding features. Over time, public pages and app screens living in the same client-rendered architecture became a constraint for SEO, speed, social sharing, content operations, and language support. We planned a staged migration to Next.js that preserved the best parts of the existing React app while adding server rendering where the business needed visibility.
Challenge
The biggest challenge was migrating without interrupting the live React app. Routing, authentication, API calls, components, and the design system had to keep working while SEO-critical pages moved into Next.js App Router, metadata, SSG, and SSR patterns. We also needed to clean up hreflang, sitemap, and canonical behavior for Japanese and English pages.
Migration Strategy
Classified Pages by Business Role
Moved public SEO pages such as services, blog, case studies, and company pages into Next.js, while preserving and gradually reorganizing authenticated app behavior from the existing React architecture.
Migrated to App Router & Metadata
Rebuilt the route structure with Next.js App Router and centralized per-page metadata, canonicals, Open Graph, Twitter Card data, and hreflang behavior.
Designed SSR/SSG and Dynamic Routes
Used static generation for blog and case study pages, SSR where fresh server-rendered content mattered, and client components for app-like authenticated workflows.
Reused Existing React Assets
Reused components, UI patterns, forms, and API clients where practical, keeping migration cost under control while gaining the SEO and rendering benefits of Next.js.
Validated Search & Contact Paths
Checked sitemap, robots, static HTML, metadata, image alt text, internal links, and contact CTAs after build so both Google and real users could understand the site.
Results
- Migrated public React SPA pages into SEO-ready Next.js pages
- Delivered page-specific content, title, description, canonical, and schema in initial HTML
- Cleaned up Japanese and English hreflang and sitemap structure
- Reduced migration cost and risk by reusing existing React components
- Strengthened the path toward free consultations and contact submissions
Conclusion
Migrating from React to Next.js is not just a framework change. It is a business decision to support search-ready public pages, app-like interaction, bilingual SEO, and stronger lead generation at the same time. IT Support in Tokyo can review your existing React app, identify which pages should move to SSR or SSG, decide what should remain client-side, and execute a staged Next.js migration. If your React app needs more organic traffic and better contact conversion, contact us for a migration review.