Techniques for providing seamless offline access to web-based interactive activity may include determining a web-based interactive activity to be made available offline, and a set of content files corresponding to the web-based interactive activity. One or more content files from a remote server can be synchronized to the client device. A web browser on the client device can be executed to launch the web-based interactive activity. When the client device is determined to be offline, dynamic activity data for the web-based interactive activity stored in the web storage integrated with the web browser of the client device can be synchronized from a web domain associated with the remote server to a local domain of the client device. The web-based interactive activity can then be accessed while offline using the dynamic activity data in the local domain of the web storage of the web browser of the client device.