App Router migration risk
Large Pages Router codebases break on RSC boundaries and async layout constraints. We migrate incrementally, route by route, with Playwright regression suites at each step.
App Router Edge-ready Core Web Vitals GDPR
Next.js Development Company for High-Traffic US and EU Applications
Next.js powers our heaviest production workloads — ANT's PropTech marketplace, REHAU's global B2B portal, Mosokna's multi-brand calculator engine. We choose between App Router and Pages Router deliberately, document the decision as an ADR, and deliver ISR strategies that keep high-traffic pages fresh within seconds.
We deliver Next.js engineering for SaaS product teams migrating to App Router, marketplace operators running ISR-heavy catalog pages, B2B portals bridging Next.js front-ends to ERP and SAP backends, and regulated industries where server-rendered accessible markup is a compliance requirement. Vercel, AWS, GCP and self-hosted Node deployments — all supported with the same delivery discipline.
Challenges
Industry challenges we solve
RSC vs client component boundaries
Over-using 'use client' defeats RSC's bundle savings. Under-using it breaks interactivity. We draw boundaries explicitly and document them as team conventions.
ISR cache invalidation at scale
Stale catalog pages surface wrong prices and OOS stock. We wire on-demand revalidation to CMS and inventory webhooks for sub-second freshness.
Vercel cost creep
Serverless function invocations and Edge Middleware charges surprise teams after launch. We model costs in staging and design routes to minimise cold-start invocations.
i18n hydration mismatches
Multi-locale apps produce HTML that mismatches client hydration when locale is detected at runtime. We align locale detection to middleware and pass it through RSC context.
Middleware chains slowing TTFB
Auth, geo-redirect and A/B middleware stacked in sequence adds 100+ ms to TTFB on every request. We consolidate and benchmark middleware paths.
Solutions
Solutions we build
SaaS dashboards
App Router dashboards with RBAC, server actions for mutations and streaming for heavy analytics panels.
Marketplaces with faceted search
ISR product catalogs, server-side facet aggregation and JSON-LD product schema for SEO and AI Overviews.
Headless commerce front-ends
Shopify Plus and Magento storefronts using App Router with cart server actions and localised checkout.
Lead-gen landing systems
Multi-locale landing pages with A/B middleware, consent-compliant analytics and CRM webhook integrations.
Multi-region multi-language sites
next-intl or next-i18next with hreflang, server-side locale detection and per-locale ISR TTLs.
Pages to App Router migration
Incremental route-by-route migration with Playwright coverage, ADR documentation and zero-downtime deployment.
Stack
Technology stack
TypeScript, React Server Components, Server Actions, Tailwind CSS, Prisma, NextAuth / Auth.js, next-intl, Vercel, AWS ECS, Cloudflare, OpenTelemetry.
Compliance
Compliance & regulations
GDPR-aligned · WCAG 2.2 AA · SOC 2-capable · CCPA-acknowledged
EU
- GDPR — consent on first paint, lawful basis, DSR automation.
- EAA 2025 — accessibility compliance for public-facing digital products.
- ePrivacy — cookie consent management and analytics opt-in flows.
- eIDAS — authentication flows for regulated identity and e-signature scenarios.
US
- WCAG 2.2 AA / ADA Title III — accessible markup, keyboard nav, screen-reader testing.
- CCPA/CPRA — consumer privacy consent, opt-out and data subject rights.
- Section 508 — federal accessibility standards for government-facing products.
- SEC EDGAR — structured data and IR-site compliance for public companies.
Shared: Core Web Vitals as deploy gates, OWASP ASVS L2, SBOM per build.
Cases
Selected Next.js case studies
PropTech · Marketplace
ANT
Property marketplace web platform with listing CMS, search and B2B admin console for US and EU operators.
Manufacturing · E-commerce
REHAU
B2B e-commerce and product configurator for a global polymer manufacturer with multi-region pricing, stock and dealer workflows.
Home Improvement · Web
Mosokna
Unified online window calculator and CRM — address-based lookup, multi-tenant Laravel + React engine powering three brand sites.
Why YuSMP
Why Next.js teams choose YuSMP
Production App Router scars
We have shipped App Router into production, not just demo projects — with real ISR, real middleware chains and real multi-locale deploys.
Self-hosted-or-Vercel agnostic
We deploy to Vercel, AWS, GCP and bare-metal Node with identical ISR behaviour and cost models you can predict.
Multi-region edge experience
Edge Middleware, Cloudflare Workers and regional ISR — we know where each adds value and where it adds complexity.
FAQ
Next.js FAQ
App Router or Pages Router — which do you recommend now?
App Router with React Server Components is our default for new projects. Pages Router is still the right call for teams with large existing codebases and limited migration bandwidth. We document the decision as an ADR and revisit it at six-month milestones.
Can you self-host Next.js or do we need Vercel?
Both. We deploy on Vercel, AWS (ECS or EKS), GCP Cloud Run and bare-metal Node servers. Self-hosted deployments get ISR via a custom revalidation endpoint and standalone output mode.
How do you handle SEO with React Server Components?
RSC renders on the server, so HTML arrives fully formed for crawlers including AI Overview agents. We add generateMetadata per route, implement JSON-LD schema, and validate in staging with Search Console URL inspection.
What is your ISR strategy for high-traffic marketplaces?
We set stale-while-revalidate TTLs per route type — catalog pages: 60 s, detail pages: 300 s, user-specific: no-store. On-demand revalidation fires from CMS webhooks to keep high-value pages fresh within seconds of a content update.
How do you handle authentication in App Router?
We use Auth.js (NextAuth v5) with the App Router adapter, or integrate existing identity providers (Keycloak, Auth0, Okta) via JWT + middleware session validation. Role-based access is enforced in Next.js middleware and mirrored on the API.
Can you migrate our legacy Next.js 12 or 13 project?
Yes. We audit page-router usage, identify RSC-incompatible patterns, migrate incrementally route by route, and run Playwright regression suites at each step. Typical Pages → App Router migration takes 4–8 weeks depending on codebase size.
Build your next Next.js application with senior US & EU engineers
Response within 1 business day. NDA on request.