redos‑detector is a JavaScript/TypeScript library (with a CLI wrapper) that analyses a regular‑expression pattern and scores how susceptible it is to Regular‑Expression‑Denial‑of‑Service (ReDoS) back‑tracking attacks. It enumerates possible matching paths, computes a back‑track score, and reports whether the pattern is safe—usable by developers, security auditors, or CI pipelines (also via an ESLint plugin) across Node, Deno and browsers.