Grumbler is an opinionated starter template for creating distributable front‑end JavaScript libraries. It bundles a pre‑configured build pipeline (Babel, Webpack, ESLint, Flow, Karma/Mocha testing, code coverage, CI integration) so developers can fork the repo, replace the example code, and publish a library without manually wiring up the tooling. It’s aimed at anyone who wants a quick, convention‑based setup for a new JS module rather than building the build system from scratch.