How I built 50+ Korean tax calculators with Next.js SSG

The Problem Calculating Korean taxes is painful. Severance pay, 4 major insurances (National Pension, Health, Employment, Industrial Accident), income tax brackets — every year the rates change, and most online calculators are outdated or ad-heavy. The Solution I built gye-san.com — 50+ free calculators covering everything from net salary to capital gains tax, all updated for 2026. Tech Stack Next.js (Static Site Generation, output: export) Cloudflare Pages for hosting (sub-1s load globally) Single JSON data file drives all 50+ calculator pages via dynamic [slug].jsx routing Key Architecture Decisions Programmatic SEO Each calculator page is auto-generated from calculators.json with: Dynamic meta titles/descriptions JSON-LD Schema (WebApplication + FAQ + BreadcrumbList) Auto-generated sitemap Internal linking between related calculators (same pillar) PWA Support Added next-pwa so users can install it as an app on mobile. Results Lighthouse: 90+ across all categories 50+ calculator page