OpenCC

OpenCC converts between Traditional and Simplified Chinese, the kind of conversion that sounds trivial until you try it. It's not a character swap. Word choice, regional phrasing, and idioms differ between Taiwan, Hong Kong, and mainland China, and OpenCC handles those variants instead of doing a naive one-to-one replace. It's a free, open source library.

It ships as a C++ library with bindings for Python, Node, and most other languages, plus a command-line tool. You feed it text and a conversion config, Simplified to Traditional Taiwan, Traditional to Simplified, and so on, and it returns properly localized output. It's the quiet standard a lot of apps and datasets rely on for this job.

Setup is trivial: install the package and call it. No service to run, no account, no cost. Reach for it any time you need to localize Chinese text correctly across regions. The catch is scope: it does this one thing. It's not translation and not general language processing. For Chinese variant conversion, though, it's the tool to reach for, and it's free.