1. What this site is
This site offers 18 handy tools across four areas: development (JSON formatter, regex tester, cron parser, timestamp converter, Base64 encoder/decoder), writing (word count, text diff, Markdown preview, line dedupe), images and design (image compressor, QR code generator and decoder, color converter), and daily life and finance (mortgage calculator, income-tax calculator, date calculator, unit converter), plus a Chinese character stroke lookup. Every tool works instantly — no pop-ups, no forced login, and no "sign up to unlock more".
Beyond the tools, there are a few long-form articles explaining how things work under the hood: how to pick a QR code error-correction level, how Chinese character strokes are counted, and how the two mortgage repayment methods really differ. The tools answer "how", the articles answer "why".
2. Why "runs locally" matters
The JSON you paste, the images you drop in, the salary figures you type — everything is computed inside your own browser and is never sent to any server. This is not a slogan but a consequence of the architecture: the site is fully static and has no back-end server that could receive your data in the first place. You can verify it yourself in your browser's developer tools: open the Network tab and use any tool — you will not see a single outgoing request.
Running locally has two side benefits: it's fast (no network round-trips), and once the page has loaded it keeps working even offline.
3. Free — so how does it survive?
Every tool on this site is free, permanently, with no paywall. Domain and hosting costs are low and covered by modest advertising and voluntary support, so there is no reason to charge users a cent — or to sell any data. If a tool here has ever saved you time, recommending it to a colleague is the best support.
4. Who maintains it
An independent developer. Most of the tools grew out of everyday frustrations of mine and my friends': a mortgage calculator without ads, a word counter that behaves itself, a regex tester that ends the tab-switching dance. Enough small annoyances piled up, and this site happened.
Every message in the feedback box gets read carefully. Accepted suggestions usually ship within the next few releases — leave your email in the feedback box and I'll let you know when your feature goes live.
5. Contact
For feature requests, bug reports, or a tool that looks broken in your browser, the feedback box is best (it automatically attaches the page and language, which makes problems easier to pin down); you can also email directly:
For questions about data collection and processing, please read the privacy policy.