An agent providing customer support to visitors on a website can co-browse with the visitors as they interact with the website. The agent is provided with a list of authorized third-party domains. Upon selection of one of the authorized third-party domains, an invitation will be sent to the visitor to co-browse with the agent on the website in the unaffiliated third-party domain. Acceptance of the invitation causes a co-browse browser extension to be downloaded to the visitor's browser and redirects the visitor's browser to the website in the third-party domain. The co-browse browser extension contains co-browse script to replicate the DOM of the visitor's browser to the agent so that the agent can view the visitor's browser as the visitor interacts with the website in the third-party domain.