I built 50 cost calculators covering home improvement, automotive, dental, and other projects. Plain HTML, vanilla JS, CSS - no framework, no npm, no build step (well, one tiny Node script to inject shared headers). Hosted on Cloudflare Pages.

Each calculator takes your project details (size, materials, complexity) and gives a low/average/high estimate based on national pricing data from contractor surveys.

The whole site is ~230KB per page including fonts (self-hosted WOFF2). Every page scores 95+ on Lighthouse. No signup, no email gate, no lead-gen popups.

Stack: Static HTML + CSS + vanilla JS. One shared calculator engine (js/calculator.js) reads a config object on each page and builds the form dynamically. Total JS is under 4KB.

Built this as part of a solo dev revenue portfolio targeting low-competition SEO keywords. Happy to answer questions about the keyword research strategy, the build process, or the monetization plan.