This tool allows you to open an HTML file in a fully sandboxed environment, extract data using JavaScript, and download the extracted data as a JSON file.
(You can use this saved JSON text file with the Prompt-backup-viewer, which also needs to be saved to the same folder that contains your saved images folder, either via right-click on the link here and save-as, or open the page and save it via control-S (Windows computer) or command-S (Mac computer).)