Change detection is the practice of monitoring a webpage for content modifications and alerting when something changes. It applies to text, images, prices, structured data, and full-page screenshots.
Change detection is broader than visual regression: it also covers DOM-level comparison, keyword presence/absence (e.g. ensuring 'Add to cart' appears on every product page), structured-data changes, and JSON-API response shape monitoring.
Triggers are configurable — alert on any change, alert only on changes to a specific selector, alert only when a keyword disappears, alert when a price moves outside a range.
Change detection catches problems no other monitor sees: a CMS user accidentally publishing a draft, a third-party widget swapping in different content, a legal page being modified without legal review, a competitor changing their pricing.
See it in the product: Change detection.