Next.js development agency in London — the framework is mature, the agencies that ship it well still are not

A Next.js development agency builds production sites and web apps on the Next.js framework (App Router or Pages Router, React 19, Server Components, server actions, streaming). The work splits three ways. (1) Greenfield builds — marketing sites, SaaS dashboards, ecommerce storefronts built from scratch on Next.js. (2) Headless front-ends — Next.js rendering content from WordPress, Sanity, Contentful, or Payload while the CMS stays in its native admin. (3) Migrations — moving existing React, Gatsby, CRA, or WordPress sites to Next.js with SEO continuity. The framework is the same; the engagement shape changes substantially across the three.

Four bands. (1) Marketing site, 5-20 pages, design provided: 12,000-35,000 USD. (2) Mid-market marketing site or SaaS dashboard, 20-100 pages, full custom design + headless CMS: 35,000-90,000 USD. (3) Ecommerce or app-shell builds with auth, payments, server actions, 100-500 pages: 75,000-200,000 USD. (4) Enterprise multi-region, ISR + edge functions + analytics pipeline: 150,000-500,000+ USD. London agency pricing runs 10-20% above US-distributed equivalents because senior Next.js talent in London is genuinely scarce.

Discovery: 1-2 weeks regardless of size. Build: 6-10 weeks (marketing site), 10-16 weeks (SaaS app shell), 16-26 weeks (ecommerce or enterprise). Cutover and post-launch monitoring add 2-4 weeks. Anything promising a 4-week production-grade Next.js build is selling a templated theme port, not engineering.

Use Next.js when you need (a) dynamic, authenticated, or personalised content that a static site cannot serve, (b) React component architecture for a design system that scales beyond a single site, (c) edge rendering or streaming for performance reasons WordPress and Astro cannot deliver, or (d) a unified codebase across a marketing site and a product app. Stay on WordPress for editorial-heavy marketing sites where the team needs full wp-admin. Choose Astro for content-led sites with mostly static rendering. Never replatform off WordPress to Next.js purely for performance — headless WordPress with a Next.js front-end usually solves the speed problem without giving up the editorial UX.

App Router for all new projects. Pages Router is in maintenance — it still works, but Vercel ships new features on the App Router first (Server Components, server actions, parallel routes, streaming) and most third-party Next.js library updates assume App Router by default. If you are joining an existing Pages Router codebase, do not rewrite — incrementally migrate routes that benefit from RSC and leave the rest. If a 2026 quote proposes Pages Router for a greenfield build, ask why.

Headless WordPress is one specific Next.js (or Astro, or Nuxt) pattern — WordPress acts as the editorial CMS and Next.js renders the front-end via WPGraphQL. Next.js development is the broader category — could be headless WordPress, could be Sanity-backed, could be a fully bespoke SaaS app with no traditional CMS. If your buyers are editorial teams using wp-admin, you want a headless WordPress build. If your buyers are end-users of a product or app, you usually want a fuller Next.js build with auth, server actions, and a backend you control.

Vercel is the default — they make Next.js, and their edge network plus build pipeline is genuinely better than the alternatives for non-trivial Next.js apps. Cloudflare Workers and Netlify both run Next.js but with caveats on edge-runtime feature compatibility. Self-hosted Next.js on AWS or Render works for sites with regulatory hosting constraints but adds 2-4 weeks of infrastructure work per project. For a London-based brand without specific hosting requirements, default to Vercel and revisit at scale.

Four questions. (1) Show me a Next.js production codebase from the last 12 months — file structure, server component patterns, data fetching strategy. (2) What is your testing setup? (Playwright + Vitest minimum; agencies skipping E2E ship regressions.) (3) How do you handle the deploy preview to production diff — are visual regression checks automated? (4) Name the senior engineer who will own the architecture decisions on my project. If they cannot do all four, the engagement will end badly.

Engineering-led agencies typically expect you to bring a design system or hire design partners separately. Design-led agencies that have learned Next.js often ship slower and with more architectural debt. The pattern that works best at mid-market scale (75,000-200,000 USD): design through a small boutique studio you trust, then bring an engineering-led Next.js agency for the build. Single-agency design + build works at the smaller end (under 50,000 USD) where there is less to coordinate.

Yes. I am based in London and run discovery and stakeholder workshops in person where it helps. The engineering itself is remote across a global delivery team — Next.js work needs deep-focus blocks rather than meeting rooms — but London-time office hours, in-person discovery, and onsite reviews are part of the engagement when it makes sense. Sydney, Melbourne, and Auckland clients covered on staggered hours.