About this site

Why it exists

Most of these tools started as something I needed and could not find a version of that I trusted. A percentage calculator that pastes a tracking script onto the page. A background remover that wants an account before it will show you the result. A PDF merger that uploads a contract to a server in order to staple two files together. The work in every one of those cases is arithmetic or image manipulation that a browser has been able to do on its own for years.

So each tool here runs on your device. There is no backend, no database and no upload step. You can watch the network tab while you use any of them and see that the file never leaves. That is the one design rule the whole site is built around, and it is why the tools are free: running them costs me nothing beyond hosting a few static files.

How the tools are built

Everything is written as a static site and served from GitHub Pages. Where a browser already provides a capability — the Web Crypto API for hashing, Web Speech for dictation, the Intl API for time zones and number formatting, canvas for image work — the tool uses it instead of shipping a library to do the same job. That keeps pages small and means fewer third parties get to see what you are doing.

Each tool page carries a written guide: what the tool computes, how to drive it, and the cases where it will not help you. Those guides are not filler. Anything doing real arithmetic — the severance and hourly-wage calculators, the loan schedules, the BMI figures — is worked out against the rule it claims to follow, and where that rule has a date or a threshold attached, the guide names it so you can check whether it is still current.

What it will not do

No tool here asks you to sign up, and there is nothing to sign up for. Nothing you type or open is transmitted to me. Preferences that persist between visits — the cities on your world clock, your calculator history — sit in your own browser storage and are gone the moment you clear site data.

The tools are also not professional advice. The pay and severance calculators implement the arithmetic of Korean labour law as it stood on the date printed in each guide, which is a different thing from a ruling on your particular contract. The BMI page returns a number that public-health bodies use for populations, not a diagnosis. Where a result matters, treat this site as a way to check someone else’s figure, not as the last word.

How it is funded

The site carries advertising through Google AdSense, and that is its only source of income. Ads are what pay for the domain and for the time spent maintaining the tools; no tool is placed behind a payment, and nothing is ranked, recommended or written differently because of an advertiser.

Analytics are limited to Google Analytics, which tells me which tools get used so I know what is worth improving. What each service collects, and how to opt out of personalised advertising, is set out on the privacy policy page.

Languages

The site is published in English and Korean. It previously carried Japanese and Chinese versions as well; those were withdrawn because the writing behind them was too thin to be worth reading in those languages, and a page that exists only to occupy a URL is not a service to anyone who lands on it. Old Japanese and Chinese links now send you to the English page rather than to an error.