I wanted to see how far I could push Astro without a backend or any UI framework. Over the last few months, I built a multilingual calculator site — 48 financial and utility calculators across 5 languages (English, German, French, Spanish, Polish), which Astro generates into roughly 370 static pages. The interesting part wasn't the math itself, but keeping the whole thing maintainable as it scaled. This post covers the architecture, the i18n approach, how I separated calculator logic from UI, and things I'd do differently. The Stack Astro — static site generation, zero client JS by default Vanilla JavaScript — no React, no Vue, just plain JS for calculator logic Chart.js — interactive charts (lazy-loaded) Netlify — hosting with automatic deploys CSS custom properties — theming and responsive design No backend. No database. No auth. Just HTML, JS, and math.…