Web App Development
Next.js Web App Development With App Router and Edge Performance
We build Next.js web apps exclusively on the App Router with Server Components, TypeScript strict mode, and Vercel deployment — fast to ship, built to scale, clean to hand off.
Why Next.js Web App Development Requires Genuine Expertise
Next.js is not just a React framework — it is a full-stack platform, and the difference between using it well and using it wrong is enormous. Developers who approach Next.js with a Create React App mindset end up with bloated client bundles, unnecessary useEffect data fetching, and API routes doing work that Server Components should handle for free. At Greta Agency, we have shipped 30+ production Next.js applications and know exactly how to leverage App Router, React Server Components, and edge functions to build web apps that are fast by default, not fast after optimization.
The Next.js 15 App Router is not just a routing upgrade — it represents a fundamentally different mental model for data fetching, caching, and code organization. Pages that were previously client components with useEffect data fetching become server components that fetch data at render time, eliminating loading spinners and improving Time to First Byte by 40–70%. Most agencies still build in the old Pages Router model because App Router is newer and more conceptually demanding. We build exclusively on App Router because the performance and DX benefits are simply too significant to ignore.
Next.js on Vercel is deceptively powerful and deceptively expensive if misconfigured. Edge functions, Incremental Static Regeneration, on-demand revalidation, and image optimization all need to be configured correctly for your specific traffic patterns. We have debugged Vercel bills that ballooned to $10,000 per month due to misconfigured ISR and unnecessary edge function invocations. We configure every Next.js deployment for performance and cost efficiency simultaneously — because a fast web app that costs a fortune to run is not a solved problem.
Our Approach to Next.js web app development
Every project follows our 4-step vibe-coding process — AI handles the boilerplate, senior engineers handle the craft. From idea to live product in 3–7 days for MVPs.
Discovery
We audit your data fetching requirements — which data changes frequently, which is static, and which needs real-time updates — and design the caching strategy before writing any code. In Next.js App Router, this decision (static vs dynamic vs streaming) shapes every page's architecture. Getting it right upfront prevents expensive refactors later.
Design
Next.js enables design patterns that were previously impossible: streaming HTML for progressively loading pages, parallel data fetching with Suspense boundaries for optimal perceived performance, and layouts that persist across navigation without re-rendering. We design UI structures that take advantage of these capabilities rather than ignoring them.
Build
Server Components for all data-fetching views, Client Components only where interactivity requires it, Server Actions for form mutations without API route boilerplate, TypeScript strict mode throughout, and Turbopack in development for sub-second hot reloads. AI generates the scaffolding; our engineers make every RSC vs Client Component boundary decision deliberately.
Launch
Vercel deployment with preview URLs per PR, production and staging environment separation, ISR configuration tuned for your content update frequency, image optimization for Core Web Vitals compliance, and a post-launch performance audit using Vercel Analytics and Google PageSpeed Insights. We target LCP under 2.5 seconds on every page.
What You Get
Every next.js web app development engagement includes these deliverables — scoped before we start, delivered before we invoice.
- Next.js 15 App Router application with Turbopack configured in development
- Server Components for all data-fetching pages with optimized caching strategies
- Client Components isolated to interactive UI elements with minimal client JavaScript
- Server Actions for all form submissions — no separate API routes for mutations
- TypeScript in strict mode with explicit return types and no any-type escapes
- Tailwind CSS design system with consistent component library
- Supabase integration for database and authentication with Next.js middleware
- Vercel deployment: production, staging, and per-PR preview environments
- Image optimization with Next.js Image component targeting Core Web Vitals
- Performance baseline: LCP under 2.5s, CLS under 0.1, INP under 200ms on all key pages
Tech Stack We Use
Next.js web app development at Greta is built on Next.js 15 with App Router, React 19, and TypeScript in strict mode — the latest stable versions, production-battle-tested. We use Turbopack for development for sub-second hot reloads, Supabase for the database and authentication layer with Next.js middleware for server-side session validation, Tailwind CSS for styling, and Vercel for deployment with automatic preview environments per pull request. For apps requiring payment processing, we integrate Stripe with Server Actions for checkout mutations. For real-time features, we use Supabase's real-time subscriptions with careful client-side cleanup to prevent memory leaks. The entire stack runs TypeScript end-to-end, with shared types between the database schema, API layer, and UI components.
Case Study
SEO Pilot — Next.js SaaS Shipped in 4 Days
SEO Pilot is a keyword research SaaS built entirely on Next.js App Router — one of our early App Router production deployments. We used Server Components for the keyword results display, Server Actions for the keyword submission flow, and Supabase middleware integration for session management. The result was a page that loaded in under 400ms on first visit, with no loading spinner on subsequent keyword queries because we cached results at the Server Component level. The founder launched from a single Twitter post and reached 500+ active users within 30 days — on the same Next.js deployment we handed over at project end.
Read full case studyPricing Transparency
Next.js web app development starts at $5,000 for an MVP-scoped application. Full-featured apps with complex data models, multiple user roles, and third-party integrations run $15,000–$35,000. Migrations from Pages Router to App Router are scoped after a codebase audit, starting at $3,000 for small apps. All projects include Vercel deployment configuration, performance audit, and one week of post-launch support.
MVP
From $5,000
3–7 business days
Full Build
From $15,000
2–4 weeks
All projects include full code ownership, two revision rounds, Vercel deployment, and one week of post-launch support. No hidden fees.
Frequently Asked Questions
Do you build on the Next.js Pages Router or App Router?
We build exclusively on Next.js 15 App Router. We do not start new projects on Pages Router. If you have an existing Pages Router app you want to migrate to App Router, we offer that as a scoped migration service starting at $3,000 for small codebases — assessed after a code audit.
What is the difference between App Router and Pages Router?
App Router uses React Server Components, which means data fetching happens on the server at render time — eliminating client-side loading spinners for initial data. It also introduces Server Actions for mutations, nested layouts, and a more granular caching model. The mental model is different but the performance improvement — 40–70% better TTFB in our measured cases — is real.
Can you migrate my existing Next.js app to the App Router?
Yes. We offer a Pages Router to App Router migration service. The scope depends on how many pages exist and how heavily the app uses getServerSideProps and getStaticProps patterns. We do a codebase audit before quoting, which takes 2–3 hours and produces a migration plan with estimated timeline and cost.
Do you use Vercel or can I deploy Next.js elsewhere?
We default to Vercel for Next.js because of its zero-config ISR, edge middleware, and deployment optimizations that are tightly coupled to Next.js. Self-hosted deployments on Railway, Fly.io, or AWS are possible but require more configuration and lose some Vercel-specific Next.js features. We recommend Vercel unless you have a specific reason to self-host.
How do you handle authentication in a Next.js App Router app?
We use Supabase Auth with Next.js middleware for server-side session validation. The middleware runs on every request, checks the session cookie, and redirects unauthenticated users before the page renders — eliminating client-side auth flicker. For enterprise SSO requirements, we use Clerk as the auth provider.
What is your approach to Next.js performance optimization?
We target Core Web Vitals thresholds: LCP under 2.5 seconds, CLS under 0.1, and INP under 200ms. Our approach: Server Components for all data-fetching views to eliminate client-side loading, Next.js Image for responsive images with automatic WebP conversion, dynamic imports for heavy UI components, and ISR for pages that can tolerate a short staleness window.
Can you build a multi-tenant SaaS on Next.js?
Yes, and we have done it multiple times. Multi-tenancy in Next.js App Router uses middleware for tenant identification via subdomain or path prefix, Supabase Row Level Security for database isolation, and a tenant configuration table for branding and feature flags. We architect this correctly from discovery — tenant isolation is too expensive to retrofit.
Do you write tests for Next.js apps?
We write Playwright end-to-end tests for critical user flows — signup, payment, core product actions — and Vitest unit tests for utility functions and business logic. We do not write component tests for every UI element, which is typically over-testing for an early-stage product. Test coverage is scoped to the paths where a failure would directly impact revenue.
Ready to ship?
Ready to build your Next.js web app?
Start Your ProjectOr reach us directly at hello@greta.agency
Written by the Greta Agency team · Last updated April 2025