--- title: "Migration to Next.js" description: "Move legacy React and SPA apps onto Next.js for server rendering, streaming, edge delivery, and measurable SEO and performance gains." url: https://www.callstack.com/services/migration-to-nextjs updated: 2026-11-09T15:59:04.239Z --- # Migration to Next.js Move legacy React and SPA apps onto Next.js for server rendering, streaming, edge delivery, and measurable SEO and performance gains. _[Expert Engineering](/ai-native-engineering) › [Migrations & Upgrades](/capabilities/ai-assisted-migrations)_ **Take your React app server-side** Client-only React leaves SEO and performance on the table. We migrate SPAs and legacy React apps to Next.js route by route - server rendering, streaming, edge delivery - without a big-bang rewrite. ## Migrations & Upgrades - React Foundation Founding Member · 300+ commits to React Native · Contributing since 2016 - Industry runs on our tooling · 50M+ OSS downloads / month - 4x More React Native pages · 30% React Native adoption - 60 → 10min Faster builds after replacing Jenkins with EAS - React Native Brownfield · Tooling for introducing React Native into existing native apps incrementally. - 100+ Enterprise projects delivered ## What you get: SSR without the rewrite. - **Incremental migration path** Route-by-route adoption behind a proxy, so the product ships while it migrates. - **Rendering strategy per page** SSR, SSG, ISR, or client rendering chosen on data and traffic, not fashion. - **Core Web Vitals gains** LCP, INP, and CLS improvements measured and tied to SEO and conversion. - **Data layer redesign** Fetching moved to the server, ending loading-spinner cascades. - **Edge and caching setup** CDN, edge runtime, and cache rules configured for your traffic profile. - **Zero-regression safeguards** Visual and behavioral checks on every migrated route before cutover. ## How we work together: Move from migration plan to rollout. ### Extend your team (1 week) Our senior engineers join your team to ship features, guide technical decisions, and strengthen delivery. - Your roadmap and workflow - Expertise shared as we work - Flexible timezone coverage ### Deliver a project (1-12 months) We take agreed work from technical planning to release, with clear responsibilities and progress you can see. - 3 Callstack engineers ship like 6 - Impact visible before sprint two - End-to-end delivery ### Solve specific challenge (as needed) We address a performance, migration, or infrastructure challenge, or run training around your team’s needs. - Focused reviews or implementation - Knowledge your team keeps - Outcomes guaranteed with contract ## What shipping at AI speed looks like. - [Modernizing a Crypto Trading Platform With React Native and Self-Hosted OTA](/case-studies/modernizing-mobile-apps-in-production-with-react-native-and-self-hosted-ota): 4x increase in RN pages across the tracked page set - [Migrating Questrade Edge Mobile to a Faster, More Scalable Architecture](/case-studies/migrating-questrade-edge-mobile-to-a-faster-more-scalable-architecture): 33% fewer re-renders across most features - [Migrating a Legacy React Native App to Expo for Faster Builds and Simplified Releases](/case-studies/migrating-a-legacy-react-native-app-to-expo-for-faster-builds-and-simplified-releases): 6x faster builds after replacing Jenkins with EAS - [Training HelloFresh Engineers to Build Production Apps With React Native](/case-studies/training-hellofresh-engineers-to-build-production-apps-with-react-native): 2.8x increase in knowledge over 8 weeks (25% → 71% assessment scores) **Faster pages, found by search.** An incremental Next.js migration with gains proven in metrics you already track. [Get my migration plan](/contact) > We had been struggling with React Native application performance until we met Callstack. > > — Huỳnh Chí Hùng, Associate Director, MOMO We’ll connect you with the right expert within 24 hours. ## Let’s find the right path for your product. **Incremental or big-bang?** Incremental, almost always. A proxy routes migrated paths to Next.js while the rest stays on the SPA, so risk stays per-route. We migrated AutoZone's storefront this way - it recovered a #1 SEO position. **What happens to our SPA routing and state?** Routing maps to the file-system router; global state usually shrinks as server data replaces client caches. We plan both explicitly per route group. **Do we need Vercel?** No. Next.js runs self-hosted, on containers, or on any major cloud. We deploy to the infrastructure your constraints require. **Are the SEO gains real?** For crawl-sensitive, content-heavy products, yes - server rendering plus Web Vitals improvements move rankings. For logged-in-only apps, the win is performance, not SEO. **App Router or Pages Router?** App Router for new work, with a pragmatic path for existing code. We do not force a double migration in one step. **How long does it take?** Driven by route count and data-layer complexity. The assessment produces a per-phase timeline before any code moves. ## Open source - [React Native Brownfield](https://github.com/callstack/react-native-brownfield): Incrementally move your iOS and Android apps to React Native without breaking - [Agent Skills](https://github.com/callstackincubator/agent-skills): Callstack’s best practices on React Native performance optimization, upgrading, CI workflows, and brownfield migrations - [React Native Community CLI](https://github.com/react-native-community/cli): Command line tools to help you build React Native apps - [React Native Builder Bob](https://github.com/callstack/react-native-builder-bob): Simple set of CLIs to scaffold and build React Native libraries for different targets - [Rock](https://www.rockjs.dev/): Modular toolkit for teams building React Native apps