From Slow WordPress to Lightning-Fast Next.js — Two Complete Websites

OsteosOnline runs osteopathy practices across Belgium and the Netherlands. Two websites—osteosonline.be and osteosonline.nl—handling thousands of patient searches monthly. The problem: They were WordPress sites. Slow. Bloated. A pain to update. Every small change required a developer. The solution: Complete rebuild in Next.js 15. Not a migration tool. Not a converter. A pixel-perfect reconstruction from the ground up.

The Process

I described what I wanted. My colleague analyzed the existing WordPress sites, extracted the design patterns, and started building. "Make the location page for Antwerpen first. That's our golden page—get that right, the rest follows." Component by component. Section by section. I reviewed on my phone, gave feedback, adjustments happened in real-time. The green accent pattern? My colleague documented it: "For cards with green background layer, use relative positioning with absolute green div at 70% width, 55% height, border-radius 24px." Every design decision captured. Every pattern reusable. When we built the NL site, we just changed the data—the components were ready.

The Scope

This wasn't a landing page. These are complete medical practice websites: • Homepage with hero, testimonials, location cards • Multiple location pages (Antwerpen, Londerzeel, Reet, Amsterdam, etc.) • Treatment pages explaining osteopathy techniques • FAQ sections with accordion components • About us, privacy policy, contact pages • Blog with articles • SEO structure that had to be preserved exactly Two websites. Two languages. Same design system. Every URL had to work. Every meta tag had to match. Google rankings couldn't drop.

What Got Built

My colleague built complete production websites:

• 90+ React components — Headers, footers, heroes, cards, accordions, testimonials, location grids, treatment sections. All typed with TypeScript
• Complete design system — 800+ lines of STYLEGUIDE.md documenting colors, typography, spacing, shadows, button variants. Reusable across both sites
• Data architecture — Location data, practitioner info, testimonials, FAQs all structured in /src/data/. No CMS needed
• SEO preservation — Exact URL structure maintained, meta tags, Open Graph, structured data (LocalBusiness), sitemap.xml, robots.txt
• Performance targets — Lighthouse 90+ across all metrics. FCP < 1.5s, LCP < 2.5s, CLS < 0.1

The Reality

Before: • Page load: 4-6 seconds • Editing: Required WordPress developer • Mobile: Barely functional • Updates: Days of back-and-forth After: • Page load: < 1.5 seconds • Editing: Change a JSON file • Mobile: Fully responsive, all breakpoints • Updates: Describe what you want, done in minutes Two complete websites. Built through conversation. No agency. No months of development. Just clear instructions and AI execution.

Why This Matters

Traditional web agency quote for this: €15,000-25,000. Timeline: 3-4 months. What it actually took: Conversations over a few weeks. Total control over every pixel. A codebase I actually understand. This is the power of AI infrastructure. Not "AI wrote some code." But "AI built production systems I couldn't have built alone." 90+ components. Two languages. Pixel-perfect. SEO preserved. That's not a demo—that's production infrastructure.