A method, web browser, and system for co-browsing online content is disclosed. Embodiments enable a co-browsing session between web browsers running on different computer systems using a respective peer proxy server on each computer system. A primary peer proxy server running on a first computer system communicates directly with a web server, while communications from other peer proxy servers running on other computer systems are directed through the primary peer proxy server. The primary peer proxy server accesses online content from the web server for presentation using a web browser running on the first computer system, where the online content is presented simultaneously with modified online content presented using web browsers running on the other computer systems. The online content and the modified online content may be synchronized based upon a web server response associated with a browser event communicated to the web server.