RozKaTool (https://asaantools.pages.dev/) started as a small set of free tools for Pakistan: a bijli bill calculator built on the real electricity tariff slabs, a salary tax calculator on the actual FBR slabs, a zakat calculator. It has now grown to 58 free tools, and the newest three are for other Asian countries: a Nepal SSF (Social Security Fund) contribution calculator, a Thailand SSO (Social Security Office) calculator, and a Bangladesh festival bonus calculator.

They are small tools. But building them taught me more about shipping for real users than any of the first forty did.

The same tool, three different rulebooks

A contribution calculator looks identical in every country: enter a salary, get a number. Underneath, the rules are completely different. Nepal's SSF splits contributions between employee and employer at fixed percentages. Thailand's SSO has a salary ceiling — contributions stop growing past it, which surprises first-time users who expect a straight percentage. Bangladesh's festival bonus is not a percentage of salary at all in the way people assume; it depends on employment rules and timing.

The lesson: a calculator is only as good as the rulebook it encodes. My rule for the whole site is that a tool must use the real published slabs and rates, never a guess. That means reading the actual scheme documents instead of copying a formula from another site. It is slower, but a calculator that guesses is worse than no calculator at all — people make real financial decisions from these numbers.

Language: simple English, no assumptions

All three new calculators are written in simple English. That was a deliberate choice after feedback on the earlier pages: the audience is all of Asia, not one country, and many users read English as a second language. Short sentences, no idioms, no jargon without an explanation next to it. "Contribution" gets a one-line explanation. "Ceiling" gets one too.

The same applies to the interface. Every calculator shows its result with the working next to it — the rate used, the ceiling applied, the split between employee and employer — so a user can check the maths instead of trusting a black box. If a number looks wrong to someone, they can see exactly where it came from.

Everything still runs in the browser

Like all 58 tools on the site, the three new calculators are plain JavaScript on a static page. No account, no uploads, no backend, no data leaving the device. A salary is sensitive information; the honest way to handle it is to never receive it at all.

That constraint shapes the code. Adding a tool means adding one folder with an index.html and a small script — no deploy pipeline beyond pushing to the Cloudflare Pages project. The new calculators each took that same shape, which is why they could be built and shipped in a day instead of a sprint.

Why "all of Asia" instead of one more local tool

Pakistan-first was the right start, but the pattern repeats across the region: people need the same everyday calculations — salary, bills, bonuses, contributions — and the big global tool sites either do not cover local schemes or bury them under sign-ups and ads. A small, free, client-side tool that gets one country's rules right is genuinely useful to millions of people who otherwise do their sums in a spreadsheet or on paper.

The next batch will follow the same rule: one country, one real rulebook, simple English, everything in the browser.

Try them

Everything is free and needs no sign-up: https://asaantools.pages.dev/ — the new calculators are at /nepal-ssf-calculator/, /thailand-sso-calculator/ and /bangladesh-festival-bonus-calculator/. The bijli bill calculator is at /bijli-bill-calculator/ and the salary tax calculator at /salary-tax-calculator/ if you want to see the Pakistan tools that started it all.

If you build tools for a specific country's rules, I would like to hear how you keep the rates up to date when the government changes them — that is the part I am still working out.