ts‑transformer‑properties‑rename is a TypeScript custom transformer that automatically renames “internal” object properties (e.g., those not exported from a library’s entry points) so they can be safely mangled by a minifier, shrinking bundle size. It’s intended for library authors and front‑end developers who use bundlers like Webpack, Rollup or ttypescript and want a zero‑refactor way to hide private‑ish fields from the public API while still keeping TypeScript typings.