A multi-touch plug-in system is described herein that exposes multi-touch data for web application developers to consume in a platform independent way. The multi-touch plug-in system receives platform-specific touch data from an operating system or touch hardware, interprets the platform-specific touch data to convert the platform-specific touch data to generic touch data, and provides the generic touch data to a hosted application running within a plug-in sandbox. Often, sandboxed environments only allow identified, trusted plug-ins to execute. By managing multi-touch data within a trusted plug-in, the plug-in can ensure that hosted applications are properly restricted to well-defined behavior, while still allowing rich features such as multi-touch interaction. Thus, the multi-touch plug-in system brings rich multi-touch interaction to a web browsing environment.