Webpage change detector / website change monitor / content diff / page-watch / visualping-style monitor / price-page monitor / status-page watcher / TOS-policy diff. Fetches a URL, strips HTML to plain text, computes a SHA-256 hash, and (when given a previous hash or text) returns a changed flag plus added/removed line lists. Optional CSS selector scopes the diff to one region. No login required; follows redirects.