A network-accessible service enables participating end users to collaborate with one another over a network. End users have computing devices that include hardware and software to enable the device to access a network. The service provides a publicly-available site or a local software application from which a first participating user initiates a “meeting,” e.g., by selecting a “share” button. In response, the site or software application provides an HTTP link that includes a “meeting” code, which may be a one-time unique code. The first participating user then shares the link with whomever he or she desires to collaborate. Upon receiving the link, a second participating user joins the meeting “on-the-fly” by simply selecting the link or navigating to the site and entering the “meeting” code. The service connects the second participating user to the meeting immediately and without requiring any registration, software download, or the like.