About

GJX Tools is a collection of 107 small utilities for developers and office work — JSON and text handling, encoding and hashing, image and PDF operations, date and finance calculators. There is no account system and no paywall.

Where your data goes

Most tools run entirely in your browser. The conversion happens in JavaScript or WebAssembly on your own machine, and the file never leaves it. Where a tool needs a server (OCR, for example), the page says so explicitly before you upload anything.

This is a design constraint rather than a marketing claim: a converter that uploads your file is a liability for both of us, and putting the computation in the browser removes an entire class of failure — including the one where a private document sits in someone else's storage.

Why the guides exist

Most tool sites explain what a button does. The guides here explain the rule behind it: why a space is sometimes %20 and sometimes +, why a password should not be hashed with SHA-256, why splitting a PDF makes it larger. If a guide and a tool disagree, the guide is the one that gets corrected.

Language

The site is primarily Chinese. The English section covers the guides and pages that are genuinely useful outside China — encoding, hashing, tokens, CSV, JSON, favicons. China-specific topics (individual income tax, severance pay, retirement age) stay on the Chinese side, because translating them would create pages nobody searches for.

The tools themselves are bilingual: open any tool and use the language toggle in the header.

Contact

Bug reports and corrections are welcome — see Contact. If you find a guide that states something wrong, that is the highest-value thing you can send.