Web App Development
SPAs, SSR apps and complex platforms — built to last, not to demo.
A web application is the core of most businesses we work with. We design and build the full stack: responsive UI, server-side logic, database models, authentication and role management, third-party integrations and the deployment pipeline that lets you ship safely on a Monday morning. Nothing is black-boxed or handed off to a junior after the scoping call.
We choose the right rendering strategy for the job — SPA where interactivity demands it, SSR or SSG for pages where SEO and first-load speed matter — and we wire it together with the testing and observability that stops you finding bugs from a customer email. The result is a codebase your own engineers can open and understand on day one.
What this covers
SPAs (React, Vue) and SSR/SSG apps (Next.js, Remix, Nuxt) — right pattern for the use case
Authentication, session management, role-based access control and multi-tenancy
Real-time features — WebSockets, live dashboards, collaborative editing
Third-party integrations: payment gateways, CRMs, communication APIs, OAuth providers
Responsive, accessible UI with consistent component architecture
Performance budgets, Core Web Vitals tuning and on-page SEO fundamentals
Unit, integration and end-to-end test suites wired into a CI pipeline
Deliverables
- A live, production-grade web application on infrastructure you own
- Source code in your repository, fully documented and CI-tested
- Deployment pipeline with staging and production environments
- Handover session covering architecture, credentials and day-to-day operations
What we build with
Web application development
A web application is software that runs in a browser, persists state on a server, and presents different experiences to different users based on identity and context. This is distinct from a static website (no server-side state per user) and from a native desktop application (not delivered via HTTP). The rendering strategy — how and where HTML is generated — is the first meaningful technical decision, and it has compounding consequences for performance, SEO, infrastructure cost, and developer experience.
Our scope covers the full request-response path: browser rendering and interactivity, API layer, authentication and authorisation, database models, third-party integrations, and the deployment pipeline that keeps the system observable and safe to change. We draw the boundary at native mobile clients (handled separately) and at heavy batch data pipelines (data engineering territory).
Principles that shape how we build web apps
These govern technical decisions across every web engagement. They are not preferences — they are the things we have learned are non-negotiable from operating systems in production.
Rendering strategy is a per-route decision
Next.js and Remix let you choose rendering mode at the route level, which is the right granularity. A marketing page belongs on a CDN edge as static HTML. A real-time dashboard requires client-side fetching. A user account page should be server-rendered with auth context baked in. Treating the whole app as one mode (pure SPA or pure SSR) is an oversimplification that creates avoidable trade-offs — either a blank screen for web crawlers, or unnecessary server load for content that never changes.
Core Web Vitals are engineering requirements
Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP) are measured by real users in the Chrome User Experience Report and feed directly into Google search ranking. We treat them as acceptance criteria, not post-launch optimisation tasks. That means lazy-loading below-the-fold assets, eliminating render-blocking scripts, reserving space for images before they load, and measuring on a throttled connection — not a MacBook Pro on fibre.
Authentication at the edge, authorisation in the business layer
Session validation — is this token real and not expired? — belongs as close to the user as possible, ideally in an edge middleware or API gateway, so unauthenticated requests never reach application servers. Authorisation — can this user do this specific action? — belongs in the business logic layer where it has access to the full domain context. Mixing the two results in scattered permission checks that are impossible to audit and easy to miss.
Code-splitting is not optional at scale
A JavaScript bundle that ships the entire application on every route is a mobile performance problem and a Core Web Vitals problem. Route-level code-splitting is a default in Next.js and Remix; component-level splitting with React.lazy is applied wherever a heavy dependency (a rich-text editor, a charting library, a PDF renderer) is loaded on a path that most users never visit. We verify bundle sizes in CI so regressions are caught before they ship.
Optimistic UI with server reconciliation
Optimistic updates — reflecting the expected state change immediately before the server confirms — reduce perceived latency and make interactive applications feel fast on slow connections. They require disciplined rollback: if the server rejects the operation, the UI must return to the correct prior state without visible corruption. We implement optimistic updates only where the success probability is high and rollback paths are explicitly handled.
How we'd choose
There's rarely one right answer — these are the trade-offs we weigh before recommending an approach.
SPA vs SSR vs SSG — choosing a rendering strategy
Rendering strategy affects SEO, time-to-first-byte, infrastructure cost, and how much JavaScript the client must parse before the page is usable. The right answer is almost always 'a combination' — but every project needs to know which mode is the default and why.
| Criterion | SPA (client-side rendering) | SSR (server-side rendering) | SSG (static site generation) |
|---|---|---|---|
| How HTML is produced | Empty shell delivered; React hydrates and fetches data in the browser | Full HTML rendered per-request on the server with live data baked in | HTML rendered once at build time; served as a static file from a CDN |
| SEO suitability | Poor by default — crawlers receive an empty shell; requires prerendering workarounds | Good — crawlers receive fully populated HTML on every request | Excellent — HTML is pre-built and instantly available; best crawl performance |
| First Contentful Paint (FCP) | Slower — browser must download JS, execute it, then fetch data before rendering | Fast — HTML arrives from the server already populated; hydration adds interactivity | Fastest — file served from CDN edge; no server compute on the critical path |
| Data freshness | Always fresh — client fetches on every load; no caching complexity at the server | As fresh as the request — data fetched per-request; suitable for personalised or real-time content | Stale until rebuild — content reflects the last build; ISR extends this with per-page TTLs |
| Infrastructure cost | Low — static CDN for the shell; API servers handle data only | Higher — origin server must handle every page request; needs scaling for traffic spikes | Lowest — files served from CDN; no server compute at runtime |
| Best fit | Internal tools, dashboards, authenticated apps where SEO is irrelevant | E-commerce PDPs, user account pages, anything personalised or requiring up-to-the-second data | Marketing sites, documentation, blogs, product catalogues that change infrequently |
Web app anti-patterns we actively prevent
Hydration mismatch left unresolved
Server-rendered HTML and the client-side React tree describe different states — commonly caused by accessing browser APIs (window, localStorage) or non-deterministic values (Date.now(), Math.random()) during the render that SSR runs server-side. React suppresses the mismatch silently in development but throws or produces visual glitches in production. The bug is often intermittent and hard to reproduce.
Isolate all browser-API access behind useEffect or dynamic imports with ssr: false. For date/time values, pass a serialised timestamp from the server as a prop rather than computing it in the component. Add a hydration smoke-test to CI that compares the server-rendered markup to the client-hydrated output and fails on divergence.
N+1 queries from unguarded data fetching
A page fetches a list of items, then renders each item as a component that independently fetches its own related data. The result is one request for the list plus one per item — a pattern that is imperceptible in development with five rows and catastrophic in production with five hundred. ORMs make this trivially easy to introduce and hard to spot without query logging.
Instrument a query logger in the development environment that prints a warning whenever more than a configurable threshold of queries fire in a single request. Design data-fetching at the page or route level, not the component level. Use DataLoader-style batching where the data source supports it, and verify the query count in integration tests for list views.
Client-side routing without loading and error states
SPA navigation that shows nothing while the next route is loading, or a blank screen when a fetch fails, forces users to wonder whether their click registered. In slow network conditions — mobile on 3G, a user in a low-bandwidth region — this is the norm, not the edge case. Missing error boundaries mean a single failed fetch unmounts the entire React tree.
Define loading and error states as explicit UI states, not afterthoughts. Use React Suspense boundaries for route-level loading and ErrorBoundary components at meaningful tree boundaries. Test on throttled connections (Chrome DevTools Network panel) before every release, not just on localhost.
Common questions
Do you build both frontend and backend, or just one side?
Both — always. We run full-stack engagements so there is one team accountable for the whole product. If you already have a backend or a frontend and need the other side built, we can slot in and work against your existing APIs or design system.
What does 'production-grade' actually mean in practice?
It means the app ships with a test suite, a CI pipeline, structured logging, error tracking, a staging environment that mirrors production, and documentation your team can read. Not a side-project deployment that works until it does not.
Related capabilities
Have something in mind?
Tell us what you're building or stuck on. The first consultation is free — no obligation, no hard sell.