Systems and methods for storing information in a web browser by dynamically generating service worker codes are provided. In one example, an online system receives a request from a client device to store data included in the request in a service worker code. The online system modifies a source code of a particular service worker code to include the data to be stored and transmits the modified service worker code to the client device. The client device receives and stores the modified service worker code embedded with the data. The client device receives a request for a particular data associated with a web page and determines that the modified service worker code contains the requested particular data. The client device retrieves the requested particular data from the modified service worker code and updates the web page with the retrieved particular data.