Client-side generation of lossless object model representations of dynamic webpages

The disclosed technology provides for generating a lossless representation of a webpage on a client device. A method can include rendering, by a client device, a webpage to be presented in a web browser at the client device, receiving an indication of user input to run a content check on the rendered webpage, calling, in response to receiving the indication of user input, a scraping function to scrape a document object model (“DOM”) of the rendered webpage in the web browser at the client device, generating a lossless representation of the scraped DOM of the rendered webpage, and transmitting, to a web content analysis system, the lossless representation of the scraped DOM to be used when running the content check for the rendered webpage. The lossless representation of the scraped DOM can be a flat object model (“FlatOM”) of the DOM of the rendered webpage.