Disclosed is a new approach for client-side contextual engagement with a website visitor. A browser loads a page containing a reference to a script file implementing a visitor client. The visitor client may store visitor client data including site rules and a visitor profile locally on the client device. The visitor client may include a context monitor for calling the decision engine, a decision engine for evaluating the site rules relative to a context defined at least partially by events occurring on the page and the visitor profile, and a widget manager for managing visitor client data persisted on the client device. The content monitor may call the decision engine when the context changes. The decision engine may determine, in real time and relative to the context, that proactive or reactive engagement(s) may be appropriate and call the widget manager to launch and display corresponding engagement channel(s) on the page.