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2025 · Web

Calzye – Free Online Calculator Suite

A free, privacy-first suite of 48+ online calculators for math, finance, HR, tax, health, and unit conversions — all running client-side with no sign-up.

Role
Solo Developer
Year
2025
Status
Live
Duration
Ongoing
Team
Solo Project
Platform
Web
Calzye – Free Online Calculator Suite — screenshot 1 of 3

Screenshot 1 of 3

How it was built

01 Problem

Online calculators are a solved problem that nobody solved well: the common ones are ad-heavy, slow, and quietly send your salary or health figures to a server. And a 48-tool site normally means 48 sets of metadata to hand-maintain.

02 Approach

Ship every calculation to the browser so no user input ever leaves the device, and treat the calculator list as the single source of truth — structured data, sitemap, robots.txt, and llms.txt are all generated from it, so adding a tool requires no SEO upkeep.

03 Architecture

Astro static output on Cloudflare Pages. A shared calculator dataset drives routing, search, category filtering, FAQ blocks, and every generated metadata artefact. Critical CSS is inlined, analytics deferred, and fonts loaded non-blocking to protect the critical path.

04 Result

A live suite of 48+ tools across math, finance, HR, health, and conversion, with dark/light theming and no flash of unstyled content — and an SEO layer that scales itself as new calculators land.

What it does

  • Live search with keyboard-navigable suggestions across all calculators
  • Category filtering (Calculators, Finance, Converters)
  • Per-calculator FAQ blocks driven by a shared FAQ dataset
  • Standard, Scientific, Financial, and Unit/EV converter calculators
  • Finance & HR tools: EMI, SIP, SWP, PF, gratuity, in-hand salary, income tax
  • Health tools: BMI, calorie/TDEE, pregnancy due date
  • ML/AI estimators: token cost, precision/recall/F1, neural network parameters
  • Dynamic sitemap.xml, robots.txt, and llms.txt generated from calculator data
  • Dark/light theme with no flash of unstyled content

Tech stack

  • Astro
  • TypeScript
  • Tailwind CSS
  • Cloudflare Pages
  • Schema.org / JSON-LD

Key numbers

calculators
48+
categories
Math, Finance, HR, Health, Converters
rendering
100% client-side
framework
Astro (static)
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