Rousseau is a lightweight JavaScript proof‑reading library that scans English text (including plain text, HTML, etc.) for common style and grammar issues such as passive voice, unnecessary “so”, weak adverbs, weasel words, spacing and capitalization errors, and more. It’s packaged as a Textlint rule (`@textlint-rule/rousseau`) and can be used programmatically or integrated into any Node.js project that needs automated writing‑quality checks, with extensibility for custom checks like spell‑checking. This tool is aimed at developers, technical writers, and content creators who want an easy‑to‑integrate linting solution for English prose.