The latest articles on DEV Community by chapoleon (@chapoleon). https://dev.to/chapoleon https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3865088%2Fd0248315-89ab-47bb-bb15-7e2bbc6beeb2.png https://dev.to/chapoleon en chapoleon Tue, 07 Apr 2026 06:29:48 +0000 https://dev.to/chapoleon/how-i-built-50-korean-tax-calculators-with-nextjs-ssg-35mf https://dev.to/chapoleon/how-i-built-50-korean-tax-calculators-with-nextjs-ssg-35mf <h2> The Problem </h2> <p>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Employment, Industrial Accident), income tax brackets — every year the rates change, and most online calculators are outdated or ad-heavy.</p> <h2> The Solution </h2> <p>I built <strong><a href="https://gye-san.com" rel="noopener noreferrer">gye-san.com</a></strong> — 50+ free calculators covering everything from net salary to capital gains tax, all updated for 2026.</p> <h2> Tech Stack </h2> <ul> <li> <strong>Next.js</strong> (Static Site Generation, <code>output: export</code>)</li> <li> <strong>Cloudflare Pages</strong> for hosting (sub-1s load globally)</li> <li> <strong>Single JSON data file</strong> drives all 50+ calculator pages via dynamic <code>[slug].jsx</code> routing</li> </ul> <h2> Key Architecture Decisions </h2> <h3> Programmatic SEO </h3> <p>Each calculator page is auto-generated from <code>calculators.json</code> with:</p> <ul> <li>Dynamic meta titles/descriptions</li> <li>JSON-LD Schema (WebApplication + FAQ + BreadcrumbList)</li> <li>Auto-generated sitemap</li> <li>Internal linking between related calculators (same pillar)</li> </ul> <h3> PWA Support </h3> <p>Added <code>next-pwa</code> so users can install it as an app on mobile.</p> <h2> Results </h2> <ul> <li>Lighthouse: 90+ across all categories</li> <li>50+ calculator pages indexed</li> <li>Zero server costs (Cloudflare Pages free tier)</li> </ul> <h2> Open Source </h2> <p>Calculator logic is available at <a href="https://github.com/chapoleon/korean-tax-calc" rel="noopener noreferrer">github.com/chapoleon/korean-tax-calc</a></p> <p>🔗 <strong>Try it live: <a href="https://gye-san.com" rel="noopener noreferrer">gye-san.com</a></strong></p> <p>Would love any feedback or suggestions!</p> nextjs showdev sideprojects webdev