The **spec‑url** package provides a `URLReference` class that extends the standard WHATWG URL API with full support for relative, scheme‑less and nullable‑component URLs, plus dedicated `rebase`, `normalize` and `resolve` operations that behave like the WHATWG spec while handling RFC 3986‑style reference transformation. It’s aimed at JavaScript developers who need a robust, spec‑compatible way to parse, manipulate, and resolve relative URLs (e.g., in browsers, Node.js, or tooling that works with file‑system paths and web URLs).