I've been quietly building a collection of free calculator tools. 70+ live, zero frameworks, zero backend.

Started in May 2026 with a simple idea: most calculator sites are either hideous, covered in affiliate spam, or take 3 clicks before you can actually use the tool. I wanted to see if clean design and instant results could win on their own.

The stack is deliberately boring — vanilla HTML, CSS, and JavaScript. No React, no database, no dependencies to break. A Node.js build script generates everything from a central JSON registry.

What's live so far:
- Finance: stamp duty, salary (UK/US/CA), mortgage, redundancy pay, compound interest
- Clinical maths: eGFR, anion gap, corrected calcium, creatinine clearance — built carefully for healthcare professionals
- Electrical: cable sizing, volt drop, max Zs tables — validated by a practicing electrician
- Tech/security: CVSS, regex tester, cron parser, password entropy, SIEM estimator
- Plus converters, probability tools, home & DIY, and a few just-for-fun ones

Where I'm at:
- Google Search Console showing impressions growing week on week
- AdSense application in review
- No backlinks worth speaking of yet — that's the next problem to solve

Happy to share anything about the build — the static site generator, the SEO approach, or how I scoped the clinical tools without a clinical validator.

simplicalcs.com if you want to have a look.

Anyone else running AdSense on a tools site — what are your CPMs like?